1996 k1500 4wd does not work

[orosendo09]

I have a 1996 k1500 z71 The 4wd does not activate it is an electronic one with buttons on the dash. The lights for either 4wd high and low just stay blinking. I have replaced the 4wd actuator and checked wiring there is power to it because when I try to activate the 4wd I can hear a thud on the front diff which is the actuator I'm assuming. I have also changed out the oil on the front and rear diff. So im not sure what the problem could be the transfer case im not to educated on it so im not sure on how to inspect and diagnose it.

 

[GoToGuy]

Have you read the owners manual about 4X operation? If you think you have skills to press on search in forum for the " factory service manuals" free downloads for your specific year. Then you'll have the information to further diagnose.
Good luck.

 

[8thNote]

I'm dealing with same issue on 96 'Burb K1500. Except on mine the lights onthe buttons come on for a few seconds when I start the truck, then go off and stay off.

If you put a jumper wire between pins 13 and 5 of the OBD2 port, the 4x4 buttons will flash codes to point you in the right direction.

 

[Schurkey]

If you put a jumper wire between pins 13 and 5 of the OBD2 port, the 4x4 buttons will flash codes to point you in the right direction.

I had no idea. I learn something every day.

 

[GoToGuy]

So what codes do get?

 

[8thNote]

Here is a description of the 4 possible codes that can flash from jumping pins 5 & 13 of obd2 port (5 is a ground pin, 13 is the transfer case pin). Mine showed code 2. It can also flash multiple codes. There will be a 3 sec pause between codes, then once all codes are flased they will flash again over and over.

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.

 

[jadedcolt]

Here is a description of the 4 possible codes that can flash from jumping pins 5 & 13 of obd2 port (5 is a ground pin, 13 is the transfer case pin). Mine showed code 2. It can also flash multiple codes. There will be a 3 sec pause between codes, then once all codes are flased they will flash again over and over.

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.

Hello, I have a similar issue in a 1996 K1500. For a while, I could not switch my truck into 4wd and one day both 4 hi and 4 lo lights started flashing and now my truck is stuck in neutral. On the forum, I do not see a 1996 factory service manual to to further look into this issue. Where might I locate the motor relay? I already believe that the encoder motor has failed and I am currently working on replacing that, but I do not want to repeat this issue again. Also, if you have any ideas on the position of the shaft the encoder motor attaches to and what positions correlate to what gear it is in, that would be much appreciated!

 

[8thNote]

Hello, I have a similar issue in a 1996 K1500. For a while, I could not switch my truck into 4wd and one day both 4 hi and 4 lo lights started flashing and now my truck is stuck in neutral. On the forum, I do not see a 1996 factory service manual to to further look into this issue. Where might I locate the motor relay? I already believe that the encoder motor has failed and I am currently working on replacing that, but I do not want to repeat this issue again. Also, if you have any ideas on the position of the shaft the encoder motor attaches to and what positions correlate to what gear it is in, that would be much appreciated!

Transfer case relay is under the dash right above the steering column.