2007 Yukon - Service 4WD

[fldin]

I have been getting the check engine light followed by a “Service 4 Wheel Drive” message lately on my 2007 Yukon, now with 170k miles. I have owned the car for a year now. The check engine light/message was intermittent initially but is steady ON now.

What I managed to do so far:
a) I lifted the car, tried all 4WD positions with the rotary control switch at the dash, but only the rear tires were rotating.
b) Tech2 reported code U0102 which is: Lost Communication With Transfer Case Control Module
c) I had an electrician check for any backed out terminal in harness connector at the transmission, but he found none. I am not sure how good this electrician was.
d) As suggested in other threads, I have measured the resistance between terminals 6 & 14 of the DLC. It is 62.5 ohms. Is this OK?
e) I have also verified the TCM fuse under hood, and pulled it for a while but that didn’t clear the code.
f) My mechanic attempted to control the 4WD using the Tech2 but that wasn’t possible due to loss of communication with TCCM.

My mechanic suspects either a defect in one of the wires in the TCCM harness, or the TCCM itself is bad. He stated that several customers got harness damages after taking their cars for polishing, but I didn’t.

My questions are:
1. Is this enough reason to eliminate other causes that could be easily identified?
2. Is there a way for me to verify that the TCCM is receiving proper power/GND supplies?
3. Does the TCCM harness pass below the seats?
4. Is there a need to remove the dash to check the TCCM harness?

Thanks.

 

[fldin]

I was expecting much more interest!

Ay idea, anyone?

 

[stevek]

I have been getting the check engine light followed by a “Service 4 Wheel Drive” message lately on my 2007 Yukon, now with 170k miles. I have owned the car for a year now. The check engine light/message was intermittent initially but is steady ON now.

What I managed to do so far:
a) I lifted the car, tried all 4WD positions with the rotary control switch at the dash, but only the rear tires were rotating.
b) Tech2 reported code U0102 which is: Lost Communication With Transfer Case Control Module
c) I had an electrician check for any backed out terminal in harness connector at the transmission, but he found none. I am not sure how good this electrician was.
d) As suggested in other threads, I have measured the resistance between terminals 6 & 14 of the DLC. It is 62.5 ohms. Is this OK?
e) I have also verified the TCM fuse under hood, and pulled it for a while but that didn’t clear the code.
f) My mechanic attempted to control the 4WD using the Tech2 but that wasn’t possible due to loss of communication with TCCM.

My mechanic suspects either a defect in one of the wires in the TCCM harness, or the TCCM itself is bad. He stated that several customers got harness damages after taking their cars for polishing, but I didn’t.

My questions are:
1. Is this enough reason to eliminate other causes that could be easily identified?
2. Is there a way for me to verify that the TCCM is receiving proper power/GND supplies?
3. Does the TCCM harness pass below the seats?
4. Is there a need to remove the dash to check the TCCM harness?

Thanks.

Have you thought about a problem with/inside the transfer case?

 

[Zed 71]

Have your mechanic check the encoder motor and sensor.

 

[fldin]

Thanks guys.
I haven't actually had the time to take it back to the workshop yet. However, the problem has been intermittent. I don't know why, but the check engine light is not always ON. And so is the 4WD indicator light (on the selector switch) and the error message in the dash.

 

[ncawd]

u0102

Did you fix your u0102 problem? My 07 Yukon is doing the same thing and I need a little help. The symptoms are as follows:
1. Service 4WD light on
2. Check engine light
3. 4WD will not work and switch lights not lit.
4. Remote start not working
5. Active fuel system not working

Anyone have this problem and know how to fix it?

 

[Floatindirty]

I have same issue on wifes tahoe. whats the fix??

---------- Post added at 02:53 PM ---------- Previous post was at 02:34 PM ----------

Im guessing the TCCM needs to be replaced?

 

[Floatindirty]

bump

 

[hammerbackj]

Just had this fixed on my 2007 under waranty. You either need to open the control motor and replace the control module or replace the entire motor. Mine had 49000 miles so I'm not sure if this was under the 50000 mile warranty for some things or under the 100000 mile power train waranty. This seems to be a know problem at the dealer. The ford garage I bought this at knew enough to call the gm dealer and they took care of it for the ford dealership no questions asked.

 

[GM Customer Service]

fldin,

You may need to have the transfer case control module reprogrammed. This is just a suggestion, not a diagnosis. I encourage you to take the vehicle in for an inspection. A certified technician will be able to offer additional information after a physical inspection.

Please keep us posted.

Louis
GM Customer Service