Okay all, I am now back with another stupid question for my ZR2.
Last week my 4WD went out. For some strange reason it has been blowing the 20Amp ATC fuse under the hood. So I went and began diagnosing it. No amber lights on the switch. Tested the switch and it is fine. So I unplugged everything on that circut and replaced the fuse. As I began plugging everything back in I had no problems with the fuse. By the way the fuse will blow with nothing on, I have a dead short. As soon as I plugged the TCCM back in I heard one of the relays kicking in instantly, so I have found my problem. Now What I want to know is.. Does ANYONE have the Schematic of the Board for the TCCM? I have actually located my dead short on the board and I do not know what the part number is for the electronic part. When looking at it you can see the discoloration of the item in question, it is no longer Silver but copper colored.
If I can find what part number this is I may be able to fix this without buying a new TCCM. I tried to search the number on the printed circuit board but no avail. S72L2Z Please see the photos.

 

Appears to be a power transistor. But without the schematic do not know exactly what type: NPN, PNP, FET..???

Could always try unsoldering it and removing it and then reconnecting the TCCM back in the ZR2 and see if the fuse still blows....to be sure it is this. Also with it out of the circuit, use a DMM to check for shorted terminals. Any discoleration on the circuit board?

Or just find a salvage yard and get another TCCM.

 

Circuit Board is fine. Just the transistor is now "copper" colored instead of silver. I just wish they had the schematic available so I know exactly which one it is.

 

Encoder motor is powered through the TCCM. If it is internally shorted and in a position the TCCM doesn't want, it can cause the 20A ATC fuse to blow. Disconnecting the TCCM would remove the short. I personally had both a internally shorted encoder motor and a blown TCCM from the internally shorted encoder motor.

Try disconnecting the encoder motor at the transfer case and then plug the TCCM in. If dead short has gone away, then replace the encoder motor and try again.

 

It isn't the motor, I pulled the TCCM out of my wifes Envoy and put it in mine... everything runs fine

The problem is I cannot get the part off of the board now. Even after removing the protective coating from that area of the board. It seems that board has so much copper in it, it is just absorbing the heat. I even tried using my heat gun set to 850 F... to no avail... Have a friend who works on circuit boards who will try to remove that this weekend. Hopefully it will come out this time.