02 z71 4x4 problems continue. New switch, new encoder, same problem.

[Ialsofkdyourdad]

Hey sorry for posting so much


So I have swapped the switch, no change


I swapped in a new encoder motor and cleaned the connectors ( no corrosion just wanted to be thorough) , no change


Before the encoder motor and cleaning I had c0308 and c0327


With the new encoder I had c0308 and c0323.


I put the old one back in and I have the same codes ( c0308, c0323) so I returned the new encoder as that clearly wasn't the issue



So I'm thinking it's either the tccm or the wiring harness. Can I get a tccm from a junk yard? I have a pick and pull near me and they have about 14 4x4 sierra 1500s from 2000 to 2002 and 2 tahoes so I was thinking if I go to one of the ones that was in a bad accident the tccm is probably fine since the truck died from impact.
Plus they only charge 20 bucks for a module.



So if it's not that what else could it be? A new harness is a last resort as I imagine that's a huge pain in the ass and expensive as well.




If neither of those are the problem Ill be at my wits end with the 4x4. Maybe rip out a manual transfer case from a base model Silverado and retrofit a manual switch. At the junk yard a transfer case is only 150 bucks

 

[PNWYukon]

Parts reviewed at the Warranty Parts Center (WPC) have a 75% No Trouble Found (NTF) rate. The only two legitimate reasons to replace the TCCM are:

^ Diagnostic Trouble Code (DTC) C0550
^ NO Communication with a scan tool.


Diagnostic Aids

^ When diagnosing a transfer case electrical control system, ALWAYS check power and ground wiring first.
^ Test the connections for intermittent or poor connections, complete plug insertion, bent pins, pushed out terminals and water contamination.

Pay particular attention to the terminal connections at the module. Spread or open terminal connections may create an intermittent contact. Do a pin drag test. Refer to the terminal testing information in the table shown.

^ After repairs are complete, ALWAYS clear DTCs from the module prior to a system function test. If codes are not cleared first, the system will not function after repair. The technician may erroneously think that the system is still down and that further repairs are needed.

 

[Ialsofkdyourdad]

View attachment 273869

Parts reviewed at the Warranty Parts Center (WPC) have a 75% No Trouble Found (NTF) rate. The only two legitimate reasons to replace the TCCM are:

^ Diagnostic Trouble Code (DTC) C0550
^ NO Communication with a scan tool.


Diagnostic Aids

^ When diagnosing a transfer case electrical control system, ALWAYS check power and ground wiring first.
^ Test the connections for intermittent or poor connections, complete plug insertion, bent pins, pushed out terminals and water contamination.

Pay particular attention to the terminal connections at the module. Spread or open terminal connections may create an intermittent contact. Do a pin drag test. Refer to the terminal testing information in the table shown.

^ After repairs are complete, ALWAYS clear DTCs from the module prior to a system function test. If codes are not cleared first, the system will not function after repair. The technician may erroneously think that the system is still down and that further repairs are needed.

I did clear the codes. And I cleaned the ground points under the driver door. I removed them and brought them back to bare metal with a grinder, reinstalled them and painted over the bare metal( if there are others please let me know)



On the encoder motor connections I spread all the pins out so they made good connections, sprayed them with alcohol.



I had asked priviously for voltage at the module and I haven't been able to find that info.

 

[Ialsofkdyourdad]

The reason I'm thinking the tccm is I saw someone on a Silverado forum having the same issues as me who fixed it by replacing the tccm

 

[Ialsofkdyourdad]

https://chevroletforum.com/forum/ta...tahoe-transfer-case-issues-c0308-c0327-51798/


Here's another person who replaced it and it fixed there vehicle

 

[PNWYukon]

Ground locations

If your plug looks like this then there are two reference voltages:

 

[Fless]

Might want to peruse these articles about the NVG246 system.

Theory of operation (Pete Huscher):

https://atracom.blob.core.windows.net/gears/2006/2006-07/2006_07_10.pdf


Diagnosing:

https://atracom.blob.core.windows.net/gears/2006/2006-08/2006_08_08.pdf

 

[Ialsofkdyourdad]

Thanks for the advice on the ground locations. I figured since its easy to swap and a cheap part I would try the tccm, and it fixed my problems, lights are back on the switch and the service 4x4 light is gone

 

[Dino009]

When you swapped out the TCCM, did you disconnect the battery and did you pay attention to connect the 4 pin connection last ? The reason im asking is because i replaced my TCCM but now have a “loss of communication with TCCM” code and none of the lifhts stay lit after starting car.

 

[Fless]

When you swapped out the TCCM, did you disconnect the battery and did you pay attention to connect the 4 pin connection last ? The reason im asking is because i replaced my TCCM but now have a “loss of communication with TCCM” code and none of the lifhts stay lit after starting car.

Have you checked the fuses? How about some info on your vehicle?

 

[Dino009]

Have you checked the fuses? How about some info on your vehicle?

Yes i pulled out the trec fuse and the ecm and replaced em both even though they were fine. I have a 2008 tahoe LT

 

[Fless]

Check #67, a J Case fuse in the underhood fusebox, if you haven't already.

 

[Dino009]

Yes i replaced that exact one. How about disconnecting the battery ? Would that reset it ?

 

[Dino009]

I wanna try everything i can before i take it into dealership.

 

[Fless]

Might get better/more suggestions if you keep this to a single thread, and not have multiple ones.

 

[Dino009]

My bad.

 

[Doubeleive]

you say you cleaned the harness up and pins, but did you do the same on the opposing end (module? side) I would try spraying it with maf cleaner or electrical contact cleaner I would image they are both pretty much the same thing, it just evaporates and leaves no residue. if you do that and the it resolves the problem then go back and apply di-eletric grease in the harness to keep it from happening again.

 

[Dino009]

Ill try this for sure. It cpuld be the problem.

 

[Dino009]

So none of that worked. Disconnected the battery hoping for a reset but nothing. Im debating of putting the old TCCM in just to see if that has communication. Then i know i gotta take the car in to get it programmed

 

[Fless]

Just noticed these last few posts are posted in the wrong year forum.

Dorman makes a replacement TCCM that has a learn procedure after installation. I'm not sure if the no-communication issue with yours would be corrected but it might be worth a try.