Push Button 4wd Help...

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EmersonHart13

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It does! You have to jumper a pin on thd OBD connector to get them to display.

The error codes are:

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.

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.

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.

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.

Problem is I do not find it overly descriptive... I start my truck, lights blink, then nothing.
 

1997chevydriver

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Yeah..... definatly leaves alot of information to be desired........

Sorry man I'm new to the whole pushbutton system so I'm not gonna be much help
 

EmersonHart13

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Any input I can get is appreciated. I don't need 4wd for a few more months but figured I would start working through the problems while I was doing other stuff on the truck.

With my luck I will need the Encoder and the TCCM and I will have replaced everything minus the wiring.
 

1997chevydriver

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Does your 4x4 work at all? do they flash all the time or only when checking for codes?
 

EmersonHart13

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No 4WD. Normally I get the initial flash, that shows the buttons work, then all lights are off. When you hit a button nothing happens, no lights and no sounds. When I do the jumper I see the above code(s).
 

1997chevydriver

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I found this.

1- Ram Standby power fault: Possible open connection or short in the TCCM fuse circuit. However, this code is often considered normal and may be caused by clearing the codes.

2 - Encoder fault: Every time the t-case position moves, the TCCM checks the encoder’s readings during the shift. If something isn't right, it will increment an error counter by 4. A successful reading decreases the counter by 1. If the counter reaches 32, the TCCM determines the encoder faulty, and bypasses 4hi. Check for loose wires and excessive dirt/moisture near all connectors.

3 – TCCM (Transfer Case Control Module) motor circuit: Basically, every time the TCCM is powered up, it tests the encoder motor. If something isn't right, it will 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 IMEDIATELY. It can cause encoder motor failure even when the ignition is off.

4 - Ram/Rom failure: Internal software failure. Pull the TCCM fuse for 3 mins. Then replace it, and cycle the ignition from off to run 5 times. Then re-check the codes. If code 4 still is present, then the TCCM must be replaced.


For OBD-II vehicles with push button between the instrument panel and the radio/HVAC control stack:


The diagnostic trouble codes are displayed on the three transfer case shift select buttons located on the instrument panel. When the 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 driver’s side. Position the ignition switch to RUN. Note the shift select buttons for blinking 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 trouble code. 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.


The error codes are:
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.
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.
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.
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.









How to fix common push button 4wd problems:

If you have codes 2 or 3 check all the encoder motor connections at the transfer case, if those check out OK, you will probably need a new encoder motor.
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.

How to replace the TCCM

The TCCM is located behind the glove box, and is accessed from underneath the dash. In order to get to it, the kick panel and black cover need to be removed. Then a 1/4" screw holds the TCCM and ECM in the dash. The middle computer is the ECM, the one on the backside is the TCCM, and on the front is the small ABS computer. Simply loosen the two 10mm nuts on each side, and they will separate.

How to fix the encoder motor

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.

Reasonably priced way - http://www.northernautoparts.com (http://www.northernautoparts.com/). The part costs around $140 with a 1 year warranty and $38 core refund when you send the old one back.

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

How to install the encoder motor

Lucky way – The only thing that needs to be removed is the encoder motor itself. Tools needed are a 10mm hand wrench and an 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. Remove the bolts and connector, then, just pull 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 back to the directions in lucky way.
 

EmersonHart13

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Yeah, I read through that. I am in the process of the Encoder reset. Since you have to wait 30 minutes between each and do it 5 times it is quite lengthy.

Interestingly there is no fix for the error code 1... I still need to crawl under and make sure all the wiring looks okay by the Transfer Case.
 
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