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4x4 Diagnostic Truck and Blazer


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#1 Farvafire

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Posted 16 December 2007 - 08:37 PM

Thanks Crusty

Ok, here's is where I am at. I disconnected the vacuum off the cable thingy under the battery box. The cable moved back. I could pull the cable with no problems. I then checked the front drive shaft. I could move it by hand no problem. I reconnected the vacuum line, started the engine, and shut it down. The vacuum thingy now pulled the cable back. I then checked the front drive shaft and could not move it, telling me the front differential is fine.

I then started testing the T-case. I took off the vacuum lines off and I could hear it suck. I reinstalled them and moved to the electrical connector for the T-case. I removed the connector, and turned the ignition on. The 4x4 lights at this point did not come on at all. I reconnected the connection to the T-case. I then pulled the battery cable off and let it set for 30 min. This will reset the TCCM (Transfer Case Control Module). At this point all the lights came back on, but still would not move from 4H,

Roy (hancockrw) called me and told me about this link that he found that tells you how to test the transfer control system. I did the steps and it told me the TCCM motor circuit was bad. This is in the transfer case actuator itself. I already had the feeling that was were the problem was, and with Roy’s help It was confirmed.

Instead of linking to it, I pasted it below so it will always be here. It’s good info.

And many thanks to Roy for finding this info. It helped me out big-time.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The diagnostic trouble codes are displayed on the three transfer case shift select buttons. The shift select buttons are located on the instrument panel. When connector pin 13 on the data link cable is grounded (and the ignition switch has been OFF for at least five seconds prior to positioning the ignition switch to RUN), the shift select buttons will blink various times together in order to indicate a diagnostic trouble code from 1 to 4.

Position the ignition switch to OFF. Ensure the ignition switch is positioned to OFF for at least 6 seconds.

Connect pin 13 on the data link cable to a vehicle ground source. The data link connector is located in the cab under the instrument panel on the drivers side.

Position the ignition switch to RUN.

Note the shift select buttons for blinking codes. Refer to Diagnostic Trouble Codes.

If the shift select buttons all blink one time and stop, and do not continue to blink, no fault codes are stored in the TCCM.

The transfer case shift select buttons will blink in order to identify any stored DTC's. If only one code is stored in the TCCM memory, that code will blink repeatedly with a three second delay between blinking sequences. If more than one code is stored, the first code will blink once, then after a three seconds delay, the next code will blink. This sequence will continue until pin 13 is no longer grounded.

When reading the diagnostic trouble codes, the number of shift select buttons blinks will indicate the code number.
---------------------------------------------------
Diagnostic Trouble Code (DTC) 1
When the ignition switch is positioned to RUN the TCCM test to determine if RAM standby Power (maintained battery power) to the TCCM was lost since the ignition was last turned OFF. When power is interrupted on pin C6 of the TCCM, the TCCM stores a loss of RAM standby power.

Diagnostic Trouble Code (DTC) 2
During electronic shifting, the TCCM check the motor/encoder for normal operation. If the motor/encoder does not function correctly enough times, the TCCM stores a motor/encoder failure DTC 2.

Diagnostic Trouble Code (DTC) 3
The TCCM performs a test each time the electronic-shift motor is turned ON or OFF. If the motor does not function properly the TCCM stores a motor circuit failure DTC 3, and the shift select buttons blink in order to inform the driver of a problem.

Diagnostic Trouble Code (DTC) 4
Each time the ignition is turned ON, the TCCM tests the memory, the program, and the internal system in order to ensure that the TCCM is operating properly. If the TCCM detects a fault within the TCCM, the TCCM stores a RAM/ROM memory failure (DTC) 4.

When the TCCM is running a diagnostic, and a code 4 is displayed by the shift select buttons, replace the TCCM.
gmshades wrote:
Electronic 4x4

What is wrong, How to fix, How to install

***HOW TO CHECK WHAT IS WRONG***

You will probably know when your 4x4 has failed when you needed it in the mud pit. Mine, for instance, failed by not doing anything when I hit the 4HI button. However, it would go into 4LO.

To read the codes for the 4x4 with electric shift transfer case, install a jumper wire from terminals "J" and "A" on the ALDL (12 pin connector under the driver's side dash)

The lights on the 4x4 indicator (switch) will flash in a pattern, there are only 4 codes, one flash is code one, 2 flashes is a code 2, and so on...

Code "1" is "RAM standby power" and is considered normal, may be caused by clearing the codes.
Code "2" is "Encoder fault"
Code "3" is "TCCM motor circuit"
Code "4" is "RAM/ROM failure"

If you have the codes 2 or 3 check all the encoder motor connections at the transfer case, if OK it will need a new encoder motor assembly.
If you have code 4, replace the TCCM.

Make sure all connections are good and no corrosion, and then it's either an encoder or TCCM.

***TO FIX THE TCCM***

The TCCM is located behind the glove box, and is accessed from underneath the dash. To remove, the kick panel and black cover come off. Then a 1/4" screw holds the "brains" in the dash. The middle computer is the Truck's brain, the one on the backside is the TCCM, and on the front is the small ABS computer. Simply loosen the 2 10mm nuts on each side, and they will separate.


***WAYS TO FIX THE ENCODER MOTOR PROBLEM.***

This is the most common problem, and was my problem.

Cheap way - To clear the codes and reset the computer, pull the 5 amp TCCM fuse, located at the bottom of the fuse box. Wait at least a half hour, and then replace the fuse. Turn the ignition key to run, wait for the 4x4 lights to blink, and then turn off. Repeat 5 times, and then start the truck.

Decent price way - I just went and bought a rebuilt encoder motor from a company off of Ebay. Their company is http://www.northernautoparts.com The part cost me around $140 with a 1 year warranty and $38 core refund when I send the old one back.

Expensive way - buy a brand new one from GM for over $300.

***HOW TO INSTALL THE NEW ENCODER MOTOR***

Lucky way - Only thing that needs to be removed is the encoder motor itself. Tools needed are a 10mm hand wrench and a 8mm and 10mm socket wrench. The 10mm socket will work on the upper and lower bolts, while the regular wrench is needed for the middle bolt. (Tight squeeze). The 8mm socket is for the electric plug.
Then, just pull out, and wiggle it out of the truck. Install in reverse order.

Unlucky way - This means the encoder motor did not just wiggle out. Now the front drive shaft will have to be removed at the transfer case. Then, a yolk puller is needed in order to remove the yolk from the transfer case. Once this is done, go to the directions in lucky way.

Writeup by gmshades

Thanks hancockrw

Encoder Signal Check

The Transfer Case Control Module (TCCM) checks the encoder signal in order to verify that the transfer case is in either 2HI, 4HI, or 4LO.

Encoder Switch Monitor Check

While the transfer case shifts, the encoder within the electric-shift motor is monitored for the proper operating sequence. If during a shift, the encoder changes to an incorrect position, an error counter in the Transfer Case Control Module (TCCM) starts to count the number of times the encoder fails. If the encoder fails eight times, the TCCM produces a Diagnostic Trouble Code (DTC) of 2 indicating an Encoder Fault. When this happens, the TCCM outputs a signal in order to default the rail shift pattern in the encoder in order to allow for only shifts into 2HI and 4LO.
In order to protect against transient, random encoder faults caused by vibration, contamination, electrical noise, etc., the error counter reduces the count by one each time a good encoder value is detected. The encoder must fail 25 percent of the time for the TCCM to store a DTC of 2 and indicate a damaged encoder.

Motor and Relay Voltage Checks

Whenever the electric-shift motor is turned ON or OFF the motor and the electrical circuits are tested both in the de-energized and energized condition. If one or both voltage relays fail to detect the proper voltage after energizing or de-energized and energized condition. If one or both of the voltage relays fail to detect the proper voltage after energizing or de-energizing, the shift is aborted by the Transfer Case Control Module (TCCM) and a Diagnostic Trouble Codes (DTC) of 3 is stored in order to indicate a faulty TCCM motor circuit. If one or both relays fail to detect the proper voltage after de-energizing, both relays are turned ON by the TCCM, (even with the ignition switch positioned OFF) in order to prevent the motor from running. The TCCM then stores a DTC of 3 in order to indicate a faulty TCCM motor circuit. All of the status lamps blink three times, stop, and repeat the blinking continuously in order to alert the driver that the electronic shift system requires immediate repair. The battery. will drain when this condition occurs, regardless of the ignition switch position.

Motor/Encoder Circuit Operation

The Transfer Code Control Module (TCCM) operates the motor/encoder in one direction by energizing one relay while the second relay is de-energized. The TCCM operates the motor in the reverse direction by energizing the second relay while the first relay is de-energized. The encoder part of the motor/encoder sends shift positioning signals to the TCCM. The motor/encoder converts a shaft position, representing a mode of range selection, into electrical signals for use by the TCCM. By interpreting the four channels (P, A, B, C) of the encoder, the transfer case control module can detect what position the transfer case is in 2HI, 4HI, 4LO, or in transition between any of the two. The four hall effect sensors of the motor/encoder are used for channels (A, B, C, and P). These sensors provide a path to ground when a magnet passes over them. A rotating magnetic ring causes the hall effect sensors voltage to drop from 5 to 0 volts. The TCCM detects the voltage of all the channels and interprets the current transfer case shift position.

Hey BTW I found this info, I know your getting code 3... may worry u a little..


3 - TCCM motor circuit : Basically, every time the TCCM is powered up, it test the encoder motor. If something isn't right, it'll trip the code 3.
Possible causes
1. Open or shorted circuit between encoder motor and TCCM
2. Short/open connection in the motor itself
3. Malfunctioning motor relay
(this can cause the indicator lights to flash all the time (normal driving). If this happens, it must be fixed IMMEDIATELY. It can cause encoder motor failure even when the ignition is off)

user posted image

I will post a picture of the data link tomorrow, if i have not given credit where it is due, let me know and i will throw your name in there. This should solve many of the repeat posts about the crappy 4x4 set up.

Edited by Farvafire, 28 April 2008 - 07:22 PM.


#2 Crusty

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Posted 16 December 2007 - 09:01 PM

Yep that info helped me!!!!! Hey Dave Thanks for the pat on the Back, Your all right in my book.... You keep them fires out you hear !!!!!

Edited by Crusty, 16 December 2007 - 09:04 PM.


#3 dabigpig

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Posted 06 March 2008 - 08:23 PM

why hasn't this been stickied yet? helped me out tremendously today biggrin.gif biggrin.gif

#4 TrUcKeR

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Posted 06 March 2008 - 09:40 PM

All grammatical errors (a ton of them) have been fixed, and this is now stickied. wink.gif

#5 Crusty

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Posted 07 March 2008 - 06:49 PM

Well it about damn time you did something useful. nutkick.gif jester.gif

No really Mike thanks for fixing it and Stickin it... It was getting old having to hunt for it all the time...


#6 dabigpig

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Posted 07 March 2008 - 09:58 PM

QUOTE
Cheap way - To clear the codes and reset the computer, pull the 5 amp TCCM fuse, located at the bottom of the fuse box. Wait at least a half hour, and then replace the fuse. Turn the ignition key to run, wait for the 4x4 lights to blink, and then turn off. Repeat 5 times, and then start the truck.


As an alternative to waiting half an hour couldn't you just pull the batt cable and try to start the truck to kill all the computers power instead? Then hook the batt back up and do the ignition key to run thing??

#7 Crusty

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Posted 07 March 2008 - 10:05 PM

Might be idunno.gif I didn't try that yet..

#8 Farvafire

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Posted 28 April 2008 - 07:19 PM

AUTO TRACK BLAZR2
By Jigg

Problem
My 4x4 is messed up somewhere. The truck won't go into 4hi, the light just blinks. If i put it in neutral and push the 4lo button, it'll go into 4lo, but the light still keeps blinking.
[/QUOTE]

Fix
I found out that the 236 (autotrac) case doesn't have a vacuum switch on the case itself, rather it uses an electrically controlled solenoid on the firewall to provide vacuum to the actuator. Well, i figured the solenoid crapped out on me or something, so i was going to replace it.

I went out to look for the part number on that solenoid, and decided to see if it had vacuum when i put the truck into 4x4 (4lo in neutral, so the truck didn't drive away on me lol.gif ). I pulled the line off that was going to the axle, and no vacuum. Then, i pulled the line going to the engine... it had vacuum. So, i hooked the engine line to the outlet that should've been for the axle, i got vacuum through the solenoid.

Hooked it back up as normal, and everything works again! (aside from my 4hi light, but i have another switch that works). Must've had some junk in the solenoid or something (very little holes coming out of that thing).

Pics:

user posted image


user posted image

Edited by Farvafire, 28 April 2008 - 07:21 PM.


#9 insane3639

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Posted 04 May 2008 - 12:57 PM

got a quick question about this where is the data link at iven never heard of that befor

#10 Crusty

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Posted 04 May 2008 - 01:55 PM

QUOTE (insane3639 @ May 4 2008, 12:57 PM)
got a quick question about this where is the data link at iven never heard of that befor

Under the steering wheel shakira.gif Same place you plug in a scanner rockon.gif

user posted image

#11 insane3639

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Posted 05 May 2008 - 07:10 PM

well ran the test and no problems but i think its my vaccuum thing what do i have to do to check it

#12 Crusty

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Posted 07 May 2008 - 07:59 PM

QUOTE (insane3639 @ May 5 2008, 07:10 PM) well ran the test and no problems but i think its my vaccuum thing what do i have to do to check it

You are going to have to check all your vacuum lines and the vac switch on top the t-case...

this might help????
0900823d801107e0.gif

 

 


Edited by Crusty, 02 May 2013 - 08:48 PM.


#13 shovel

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Posted 13 August 2008 - 08:39 PM

Only of anecdotal value but...

2001 Blazer with 3-button 4wd,

I hadn't used 4x4 for about 3 weeks, (well that's pretty usual.. I don't lock down every weekend even though I'd love to wink.gif ) and needed to overcome a couple rocks that 2wd wasn't quite handling... pressed 4L and both 4H and 4L buttons blinked, then returned to illuminating 2H. I tried 4H, it blinked both and returned to 2H. Tried 4L again and it illuminated 4L as though it had shifted, but I was still in 2H (no power to front wheels, and gear range was still high) ... then after I drove a few hundred feet the 2H button re-illuminated. Tried 4L again and it shifted to 4L properly like it should. Tried 4H and it wouldn't shift to 4H at all, just blinked 4H and 4L lights and then returned to 2H.

Next day I was on flat dirt & tried to re-create the problem - same symptoms. So I did some reading here, unplugged the fuse for "4WD" in my dash fuse box, waited 40 mins & replaced it... still same problems as before.

Disconnected negative battery cable under hood, put key in ignition and turned on everything I could turn on... basically to vamp out any electricity "hiding" in any electronics (the odd capacitor & such) ... waited 10 minutes, then turned everything off, reconnected battery cable.. started truck and tested 4wd - everything shifted and worked like new.

So chalk one up for a simply confused TCCM or such. Hey sometimes we luck out & don't have to spend money!

#14 ebbtide

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Posted 15 September 2008 - 03:57 PM

in this pic

can anyone tell me where the hose going to the front axle routes or where it plugs into the front axle? I looked at this actuator and found that at some point that hose has become disconnected but can't spot it laying in the engine bay there. I'm looking for a probable path to seek it..

Thanks for the help!

#15 Scott

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Posted 12 October 2008 - 05:49 PM

QUOTE (ebbtide @ Sep 15 2008, 04:57 PM) <{POST_SNAPBACK}>
can anyone tell me where the hose going to the front axle routes or where it plugs into the front axle? I looked at this actuator and found that at some point that hose has become disconnected but can't spot it laying in the engine bay there. I'm looking for a probable path to seek it..

Thanks for the help!

Front firewall over to pass side of engine then to under battery box.Mine was melted to valve cover.

#16 zr2innc

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Posted 17 November 2008 - 12:27 PM

Just a quick question for everyone. I had my engine replaced in August, and everything seemed OK, it ran great. Until this weekend when I needed my 4 wheel drive. I pushed the 4hi and it seemed normal light came on like it was engaged, however I had no power to the front wheels. Same thing when I tried 4lo, the truck geared down but still no power to the front wheels. I am going to try disconnecting the battery and turning the switch to see if that will reset the TCCM, but if anyone else has any ideas please let me know. I dont know if it has anything to do with the motor replacement.

Thanks

Jeff

#17 Crusty

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Posted 17 November 2008 - 03:22 PM

QUOTE (zr2innc @ Nov 17 2008, 12:27 PM) <{POST_SNAPBACK}>
Just a quick question for everyone. I had my engine replaced in August, and everything seemed OK, it ran great. Until this weekend when I needed my 4 wheel drive. I pushed the 4hi and it seemed normal light came on like it was engaged, however I had no power to the front wheels. Same thing when I tried 4lo, the truck geared down but still no power to the front wheels. I am going to try disconnecting the battery and turning the switch to see if that will reset the TCCM, but if anyone else has any ideas please let me know. I dont know if it has anything to do with the motor replacement.

Thanks

Jeff

Check for a vacuum leak... they might not have hooked up all the vacuum lines or got them going to the wrong areas... Also if you have a blazer with auto track check the vacuum solenoid on the firewall....

#18 zr2innc

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Posted 17 November 2008 - 07:42 PM

Looks like Ive got some checking out to do! My Actuator for the air hoses that is shown above is not even there. I found some hoses but not sure which ones should be connected to it. I found one hose that has a plug in one end and it is burnt in half from my headers. I found a transmission bolt under my truck caught by the transfer case, and another one is loose about half way out, and its gonna be a bi#$@ getting to that one. Anyway I guess I will be running over my truck to see what else I can find. If anyone knows a little about this any advice would be greatly appreciated. I will start at auto parts store to see if I can find that actuator and some vacuum lines. And I think I will stop by and have a nice chat with the guys who put in my motor. Anyway thanks for now.

Jeff


#19 wolfzr2

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Posted 02 February 2009 - 10:45 AM

This is what i found in my GM sevice CD


3 Button 4WD trouble shooting

Diagnostic Trouble Code (DTC) Displaying
The transfer case shift control module is equipped with the ability to store diagnostic information, which is useful to a technician in the event of module, component or wiring failures. This information can be retrieved from the transfer case shift control module by way of flash codes, which are displayed on the three transfer case shift control switch buttons. These buttons are located on the instrument panel to the right of the steering wheel Before obtaining DTCs, perform the following transfer case control module (TCCM) Self-Test.

TCCM Self-Test
1. Observe the transfer case shift control switch indicators while turning the ignition switch to RUN. A properly operating system will flash all indicators and then will return to the current gear. If the system is operating normally, then proceed to Displaying Codes.
2. If the TCCM failed the Self-Test, then test the following circuits.
o Battery Positive Voltage (40 and 1640), and Ignition 3 Voltage for battery voltage
o Ground Circuit for ground
o Diagnostic enable circuit for an open or high resistance
o Transfer case shift control switch connector
3. If the above circuits are normal but the TCCM still fails the Self-Test, replace the TCCM. Refer to Transfer Case Shift Control Module Replacement .

DTC Displaying
1. Turn OFF the ignition for 10 seconds.
2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
3. Turn ON the ignition, with the engine OFF.
4. Observe the transfer case shift control switch select buttons for flashing codes. Refer to Diagnostic Trouble Code (DTC) List .
Important
If the transfer case shift control switch buttons all blink only once and then stop, no fault codes are stored in the transfer case shift control module.
• When one DTC is stored in memory, that code will blink that number of times followed by a 3 second pause and then repeat.
• If more than one code is stored, the first code will blink, followed by a 3 second pause and then the second code will blink.
• This sequence will continue until PIN 13 on the DLC is no longer grounded.
• If the TCCM will not communicate the presence or absence of DTCs, test the above circuits in Self-Test Step 2. If the circuits are complete, then replace the TCCM. Refer to Transfer Case Shift Control Module Replacement .
________________________________________
Document ID# 642958
2003 Chevrolet S10 Pickup - 4WD
Diagnostic Trouble Code (DTC) Clearing
The transfer case shift control module is equipped with the ability to store diagnostic information which is useful to a technician in the event of a module, component or wiring failure. DTCs should not be cleared from the transfer case shift control module until these codes have been recorded or servicing the system has lead you to a repair and directed you to perform the "Clearing Flash Codes" operation. The following steps provide an easy way of clearing the flash codes properly.
1. Turn OFF the ignition.
2. Remove the 10 amp CTSY LP fuse from the IP fuse block.
Important
Replacing the fuse before the specified time may result in not clearing the DTCs.
3. Wait a minimum of 60 seconds before replacing the fuse. Once the fuse is replaced DTC 1 will be set in the transfer case shift control module.
4. Cycle the ignition switch from the OFF position to the RUN and back OFF five times in order to clear DTC 1 from the transfer case shift control module memory.
5. Verify that the DTCs have all been cleared. Refer to Diagnostic Trouble Code (DTC) Displaying .
DTC 001

Circuit Description
The transfer case shift-control module normally has battery voltage supplied through the battery positive voltage circuit (CKT 40) at all times. When the ignition is ON, the transfer case shift control module conducts a self-test. This self-test determines if the current memory is the same memory that was retained when the ignition was last turned OFF. This self-test indicates whether the RAM standby power-supply to the transfer case shift control module pin C6 was interrupted. If the power is interrupted, the DTCs would be cleared from memory. If the self-test fails, the transfer case shift-control module sets DTC 1.

Conditions for Clearing the DTC
This DTC will clear when the voltage supply failure has been corrected and the ignition switch has been cycled 5 times.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step inspects the CTSY LP fuse for an open.
3. This step test the battery positive voltage circuit, CKT 40, for an open or high resistance.
4. This step rechecks the CTSY LP fuse for an open.
5. This step tests the battery positive voltage circuit, CKT 40, for a short to ground.

DTC 1 - RAM Standby Power Loss
Step
Action Yes No
Schematic Reference: Transfer Case Control Schematics

1 Important
Check the transfer case shift control module for DTCs. The transfer case shift control module is not a class 2 device. DTCs are displayed on the transfer case shift control switch. Use the following four steps to obtain DTCs.
1. Turn OFF the ignition for 10 seconds.
2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
3. Turn ON the ignition, with the engine OFF.
4. Observe the transfer case shift control switch select buttons for flashing codes.
Did you perform the Diagnostic System Check-Transfer Case? Go to Step 2
Go to Diagnostic System Check - Transfer Case

2
Important
This code can get set falsely due to the improper clearing of DTCs or replacement of a blown CTSY LP fuse.
Inspect the CTSY LP fuse for an open.
Was there a problem found? Go to Step 4
Go to Step 3

3
• Test the battery positive voltage circuit, CKT 40, for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
• Cycle the ignition 5 times. Check to see if DTC 001 has cleared.
Has DTC 001 cleared? Go to Step 7
Go to Step 6

4
1. Replace the fuse.
2. Drive the vehicle under various road conditions and retest the fuse.
Did the fuse blow again? Go to Step 5
Go to Step 7

5
Test the battery positive voltage circuit, CKT 40, for a short to ground. Refer to Circuit Testing , and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition? Go to Step 7
Go to Step 6

6 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .
Did you complete the replacement? Go to Step 7
--
7 1. Clear all DTCs from memory. Refer to Diagnostic Trouble Code (DTC) Clearing .
2. Operate the vehicle while pressing each of the buttons on the transfer case shift control switch.
Does the DTC reset? Go to Step 2
System OK
________________________________________
DTC 002

Circuit Description
The transfer case encoder motor is an assembly which houses 4 separate channels. These channels are used to indicate to the transfer case shift control module the present gear position of the transfer case or if the transfer case is in transition between gears. The encoder motor assembly consists of an electronically conductive inner ground ring in contact with a 3 legged wiper arm. Each leg's length is such that it makes contact with the conductive regions of the 4 channels. When any leg of the wiper arm is making contact with the conductive area of any channel, the encoder provides a path to ground to the inner ground ring.
During electronic shifting, the transfer case shift control module monitors the transfer case encoder circuit for the proper operating sequence. If at any time during a shift, the encoder changes from one position to any position other than the next possible position, an error counter in the transfer case shift control module increments by 4. After the counter reaches 32, the transfer case shift control module set a DTC 2, a permanent "encoder fault," and reverts to a 2HI to 4LO or a 4LO to 2HI shift pattern only. To guard against a transient, random encoder fault due to vibration, dirt, electrical noise, etc., the fault counter reduces by one each time the transfer case shift control module detects a valid encoder value. The encoder must intermittently fail 25 percent of the time for the transfer case shift control module to consider it faulty and store DTC 2. It is imperative that the technician test-drive the vehicle and request several shifts in order for this code to properly be set.

Conditions for Clearing the DTC
The condition for setting the DTC is no longer present and a momentary loss of battery power at the battery positive voltage circuit, CKT 40.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step measures the voltage between the transfer case encoder circuit channels P, A, B, and C to ground.
3. This step tests the suspect circuit for an open, short to power, or short to ground.
4. This step tests the encoder signal ground circuit for an open or high resistance.

DTC 2 -- Encoder Fault
Step
Action Value(s) Yes No
Schematic Reference: Transfer Case Control Schematics

1 Important
Check the transfer case shift control module for DTCs. The transfer case shift control module is not a class 2 device. DTCs are displayed on the transfer case shift control switch. Use the following four steps to obtain DTCs.
1. Turn OFF the ignition for 10 seconds.
2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
3. Turn ON the ignition, with the engine OFF.
4. Observe the transfer case shift control switch select buttons for flashing codes.
Did you perform A Diagnostic System Check - Transfer Case? -- Go to Step 2
Go to Diagnostic System Check - Transfer Case

2
1. Disconnect the connector at the encoder motor.
2. Turn ON the ignition, with the engine OFF.
3. Measure the voltage between the transfer case encoder circuit channels P, A, B, and C to ground.
Does the voltage measure near the specified value? 4.8-5.1 V Go to Step 4
Go to Step 3

3
Test the suspect circuit for an open, short to power, or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition? -- Go to Step 7
Go to Step 6

4
1. Turn the ignition switch OFF.
2. Test the encoder signal ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition? -- Go to Step 7
Go to Step 5

5 Replace the transfer case encoder motor. Refer to Transfer Case Motor/Encoder Replacement .
Did you complete the replacement? -- Go to Step 7
--
6 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .
Did you complete the replacement? -- Go to Step 7
--
7 1. Clear all DTCs from memory. Refer to Diagnostic Trouble Code (DTC) Clearing .
2. Operate the vehicle while pressing each of the buttons on the transfer case shift control switch.
Does the DTC reset? -- Go to Step 2
System OK
DTC 003

Circuit Description
This code indicates that the transfer case encoder motor circuits are not functioning properly. One of the following conditions may exist.
• One of the internal power relays in the transfer case control module (TCCM) is not energizing or de-energizing.
• An open exists in the Battery Positive Voltage, Ground, Motor Control A or Motor Control B circuits.
• A short to ground exists in the Battery Positive Voltage, Motor Control A or Motor Control B circuits.
• A short exists within the motor or TCCM.
The transfer case encoder motor has a bi-directional, permanent magnet, D.C. motor. When a shift request is made by the TCCM, voltage will be applied through one of the motor control circuits and the TCCM will provide the ground through the other motor circuit. When a shift is requested in the opposite direction, the TCCM will reverse polarity on these two circuits. The motor through a series of gears, rotates a shaft which moves the mode and range forks to shift the transfer case between gears.

Action Taken When the DTC Sets
The TCCM utilizes an error counting system when setting this code. When the TCCM detects a circuit error, the counter will log a count of 4. When the system operates correctly, the counter will reduce by a count of 1. A total count of 32 must be reached in order for DTC 003 to be set. The system must malfunction at least 25 percent of the time in order for a DTC 003 to be set. It is imperative that the technician test drive the vehicle and request several shifts in order for this code to be properly logged.
In the event that one of the internal TCCM power relays is stuck in the energized state, the TCCM will energize the other motor control circuit to keep the motor from running. All of the transfer case control switch indicators will flash continuously to prompt the driver that service is required. The transfer case system will be disabled and the TCCM power relays will remain energized even with the ignition in the OFF position. This may cause the battery to discharge. Any other condition that sets a DTC 003 will not follow this routine but a fault code will be stored.

Conditions for Clearing the DTC
The condition for setting the DTC is no longer present and a momentary loss of battery power at the battery positive voltage circuit .

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests the power control relays inside the TCCM.
3. This step tests for voltage to the ATC/4WD fuse.
4. This step tests the ATC/4WD fuse.
5. This step tests for a voltage polarity change at the motor.
6. This step tests for voltage at circuit 16 Battery Positive Voltage.
7. This step tests for continuity to ground at circuit Ground.
8. This step tests for continuity on motor control A and B circuits.
9. This step tests for a grounded or shorted motor.
10. This step tests for a short to ground on circuit 16 Battery Positive Voltage.
11. This step tests for a short to ground on circuits Motor Control A and Motor Control B.
Step Action Value(s) Yes No
Schematic Reference: Transfer Case Control Schematics

1 Important
Check the transfer case shift control module for DTCs. The transfer case shift control module is not a class 2 device. DTCs are displayed on the transfer case shift control switch. Use the following four steps to obtain DTCs.
1. Turn OFF the ignition for 10 seconds.
2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
3. Turn ON the ignition, with the engine OFF.
4. Observe the transfer case shift control switch select buttons for flashing codes.
Did you perform the Diagnostic System Check - Transfer Case? -- Go to Step 2
Go to Diagnostic System Check - Transfer Case

2
1. Start the vehicle.
2. Request a mode shift between 2HI and 4HI.
3. Observe the transfer case shift control indicator lamps.
Are all of the lamps flashing together? -- Go to Step 17
Go to Step 3

3
Test the voltage to the ATC fuse.
Does the test light illuminate? -- Go to Step 4
Go to Step 15

4
1. Remove the fuse.
2. Observe the fuse element.
Is the fuse open? -- Go to Step 9
Go to Step 5

5
1. Disconnect the motor harness connector.
2. Turn the ignition switch RUN with engine OFF.
3. Put the transmission in Neutral.
4. Connect a DMM between Motor Control A and Motor Control B circuits.
5. Have a helper request changes by alternately pressing 4HI and 4LOW.
Does the polarity change according to the specified value? +Battery Voltage/-Battery Voltage Go to Step 16
Go to Step 6

6
1. Turn the ignition switch to OFF.
2. Disconnect the TCCM harness connector.
3. Test for voltage at both of the Battery Positive Voltage circuits at the TCCM.
Did the test light illuminate on both tests? -- Go to Step 7
Go to Step 12

7
Test for continuity to ground at the ground circuits at the TCCM.
Did you have continuity on both tests? -- Go to Step 8
Go to Step 13

8
Test for continuity on Motor Control A and B circuits.
Did you have continuity on both tests? -- Go to Step 17
Go to Step 14

9
1. Turn the ignition switch to OFF.
2. Disconnect the motor harness.
3. Set the DMM for continuity.
4. Connect the DMM to the body of the motor and pin 6 on the motor.
5. Connect the DMM to the body of the motor and pin 7 on the motor.
6. Connect the DMM across pins 6 and 7 at the motor.
Did you measure continuity, 0 Ohms, on any of the three tests? -- Go to Step 16
Go to Step 10

10
Important
Make sure you do not contact the positive side of the fuse terminal. Sending power to the DMM when checking continuity may damage the meter.
1. Remove the harness connector from the TCCM.
2. Remove the ATC fuse.
3. Connect one lead of a DMM to a known ground and the other lead to the ground side of the ATC fuse terminal.
Do you have continuity? -- Go to Step 12
Go to Step 11

11
1. Disconnect the motor connector.
2. Test for a short to ground on the Motor Control A and Motor Control B circuits.
Do you have continuity on either test? -- Go to Step 14
Go to Step 17

12 Repair the Battery Positive Voltage circuit for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair? -- Go to Step 18
--
13 Repair the ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair? -- Go to Step 18
--
14 Repair Motor Control A or Motor Control B circuits for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair? -- Go to Step 18
--
15 Repair the open circuit to the ATC fuse. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair? -- Go to Step 18
--
16 Replace the transfer case encoder motor. Refer to Transfer Case Motor/Encoder Replacement .
Did you complete the repair? -- Go to Step 18
--
17 Replace the transfer case control module. Refer to Transfer Case Shift Control Module Replacement .
Did you complete the repair? -- Go to Step 18
--
18 1. Connect all of the connectors.
2. Install a new ATC fuse.
3. Clear all DTCs from memory. Refer to Diagnostic Trouble Code (DTC) Clearing .
4. Operate the vehicle while requesting mode and range shifts.
Does the DTC reset? -- Go to Step 01
System OK
DTC 004

Circuit Description
At each power up the transfer case shift control module runs a self test on the following:
• EEPROM Checksum
• ROM Checksum
• RAM Checksum
• RAM Malfunction

Conditions for Running the DTC
• Critical operational parameters stored in EEPROM have failed Checksum test indicating invalid data.
• Masked ROM code has failed Checksum test indicating that masked ROM data is not valid.
• ROM code has failed Checksum test indicating that ROM data is not valid.
• One or more ROM locations have failed operational test indicating that some portions of RAM are not functional.

Conditions for Clearing the DTC
The condition for setting the DTC is not present and a momentary loss of battery power at the battery positive voltage circuit, CKT 40.

Test Description
The number below refers to the step number on the diagnostic table.
2. This step replaces the transfer case shift control module.

DTC 4 - RAM/ROM Failure
Step
Action Yes No
Schematic Reference: Transfer Case Control Schematics

1 Important
Check the transfer case shift control module for DTCs. The transfer case shift control module is not a class 2 device. DTCs are displayed on the transfer case shift control switch. Use the following four steps to obtain DTCs.
1. Turn OFF the ignition for 10 seconds.
2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
3. Turn ON the ignition, with the engine OFF.
4. Observe the transfer case shift control switch select buttons for flashing codes.
Did you perform the Diagnostic System Check-Transfer Case? Go to Step 2
Go to Diagnostic System Check - Transfer Case

2
Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .
Did you complete the replacement? Go to Step 3
--
3 1. Clear all DTCs from memory. Refer to Diagnostic Trouble Code (DTC) Clearing .
2. Operate the vehicle while pressing each of the buttons on the transfer case shift control switch.
Does the DTC reset? Go to Step 2
System OK


#20 slacker1357

slacker1357
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Posted 23 September 2009 - 04:24 PM

where in the hell in this Encoder motor?

This seems to be what is wrong according to the flashing code 2, by jumping 4 and 13.

I just dont really know what Im looking for...

any help appreciated. kinda sux trying to diagnose crap right after work...




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