Cel u0102 - Chevrolet Forum - Chevy Enthusiasts Forums
Typerod's Avatar
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March 25th, 2011, 10:24 AM   #1  
Cel u0102

So some past info on my situation, I wanted my s/w on my 07 Tahoe update. Got it done last December (2010). Then started having "service 4 wheel drive" popping up in my DIC when I first start my car. Car would move in and out of 2 high, auto, 4 high, and 4 low just fine. Brought it back a few weeks ago, just to have it checked out. So the tech who updated it in December put in the wrong s/w, btw he no longer works there. So another tech had a difficult time updating the s/w to its correct form, so he had to manually update each option, or something like that. The following day the "service 4 wheel drive" comes up again, and everyday since. And now yesterday, I get a check engine light, when to Advance auto, and the code is U0102, lost communication with transfer case module.

I had it cleared...I hope its just due to s/w issue. It came back on later yesterday, the check engine light that is, and I noticed that on **** to change the drive setting (auto, 4 high etc) no light was on to tell me what state the trans case was in. I went and switched to diff. settings and still nothing, then a few minutes later, I looked down and I see the light is on indicating im in 2 high, which it what i knew it was in.

Going to bring it back in next week, gotta get a few other things replaced, my adjustable pedal no longer adjust and my passenger side view mirror doesnt move up and you tilt it down past a certain point.

Has anyone experience this issue with the trans case module? is it going bad, can it go bad? is it expensive to replace? any other thoughts are appreciated! TIA!

 
genius's Avatar
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July 29th, 2011, 1:24 PM   #2  
Wow--same story!

Posted By: Typerod So some past info on my situation, I wanted my s/w on my 07 Tahoe update. Got it done last December (2010). Then started having "service 4 wheel drive" popping up in my DIC when I first start my car. Car would move in and out of 2 high, auto, 4 high, and 4 low just fine. Brought it back a few weeks ago, just to have it checked out. So the tech who updated it in December put in the wrong s/w, btw he no longer works there. So another tech had a difficult time updating the s/w to its correct form, so he had to manually update each option, or something like that. The following day the "service 4 wheel drive" comes up again, and everyday since. And now yesterday, I get a check engine light, when to Advance auto, and the code is U0102, lost communication with transfer case module.

I had it cleared...I hope its just due to s/w issue. It came back on later yesterday, the check engine light that is, and I noticed that on **** to change the drive setting (auto, 4 high etc) no light was on to tell me what state the trans case was in. I went and switched to diff. settings and still nothing, then a few minutes later, I looked down and I see the light is on indicating im in 2 high, which it what i knew it was in.

Going to bring it back in next week, gotta get a few other things replaced, my adjustable pedal no longer adjust and my passenger side view mirror doesnt move up and you tilt it down past a certain point.

Has anyone experience this issue with the trans case module? is it going bad, can it go bad? is it expensive to replace? any other thoughts are appreciated! TIA!
Holy crap! I did a google of the same thing and your story popped up and it's EXACTLY the same symptom I'm having.

I took mine into Jiffy lube for an oil change and then I started getting the "service 4 wheel drive" on the DIC. It happens every time I start it and goes away within 30 seconds--sometimes longer. Also, all the indicator lights are out on the 4x4 ****. Then it wakes up like nothing happened.

Onstar says it's U0102. Sometimes the CEL goes out and comes back. I took it to the dealer yesterday in Prince Frederick, MD where i bought it (Bayside) and $68 later, they tell me they have no idea what's wrong but the 4 wheel drive seems to be working. He says he would need to call engineering and it would take hours to figure out. I'm in the military driving to Alaska on Saturday and I'll be stuck staring at a CEL for 4300 miles.

I can turn a wrench but I've never worked on 4 wheel drive systems before... wtf do I do now?!?

There has to be someone else out there with the same problem who knows something about this... please?!?

 
genius's Avatar
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July 29th, 2011, 6:09 PM   #3  
OK so update, just in case anyone is actually paying attention. The service 4wd lit has been staying on constantly now and the 4wd switch lights are off and unresponsive. Also got a solid cell U0102. Encoder motor? Since there is a cell, it can't be the swith, right?

From what I can tell, the encoder looks simple in the 2007 TAHOE. I don't even see a need to drop the drive shaft. But whats this thing I'm reading about shifting the transfer case to neutral? I don't see any way on how to do that. I mean I can put the tranny in neutral. Looks like a pop and swap, really. Am I wrong?

I got to drive to AK this weekend. I guess I got to deal with it up there in two weeks.

 
dmatre's Avatar
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July 31st, 2011, 7:36 AM   #4  
Look at the buttons on the dash. There is an "N" off to the side, with a line going to two of the control buttons, 2hi and 4hi if I recall correctly, hold those two in simultaneously and the transfer goes to nuetral.

Set the park brake or block the wheels, becasue "P" won't hold it with the transfer in neutral.

Checked the 4wd controls last night. The word nuetral is printed between 2hi and 4hi, with a line going out to the right where it intersects a vertical line which connects to 2hi nad 4lo, so holding 2hi and 4lo simultaneously will shift the transfer to nuetral.


Last edited by dmatre; August 1st, 2011 at 8:03 AM.
 
iamgeniusrnti's Avatar
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August 13th, 2011, 10:54 PM   #5  
Posted By: dmatre Look at the buttons on the dash. There is an "N" off to the side, with a line going to two of the control buttons, 2hi and 4hi if I recall correctly, hold those two in simultaneously and the transfer goes to nuetral.

Set the park brake or block the wheels, becasue "P" won't hold it with the transfer in neutral.

Checked the 4wd controls last night. The word nuetral is printed between 2hi and 4hi, with a line going out to the right where it intersects a vertical line which connects to 2hi nad 4lo, so holding 2hi and 4lo simultaneously will shift the transfer to nuetral.
All I have is a ****, no buttons.

Sorry it took so long to get back. I was driving thru Canada on our move to Alaska. Oddly enough after about 350 miles of straight driving, the cel went away, the four wheel drive system turned back on and the truck is acting like nothing ever happened. The problem just disappeared.

 
genius's Avatar
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August 31st, 2011, 4:57 PM   #6  
So yea, a month later the problem is starting all over again. Start truck, get Service 4X4, then a day later CEL again. The 4X4 system does turn on after a few seconds to a few minutes of driving.

The CEL is U0102. Now what do I do?

 
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September 28th, 2011, 5:31 PM   #7  
My 07 Tahoe is doing the exact same thing, DIC says service 4x4, light not working on the 4x4 ****, and engine light on with the code U0102. The dealer in Fredicksburge, Va is saying it's the wiring harness or the control transfer case module or both. It's going to cost me anywhere from 250 to 600 dollars to repair. Does this sound right? Any advise for me? Thanks, Jess

 
genius's Avatar
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September 29th, 2011, 9:46 AM   #8  
This forum is very quiet and wont provide much info so let me help you out. I finally just replaced the switch and it fixed the problem! It took about 50 miles before everything woke up.

 
Jacjessies's Avatar
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September 30th, 2011, 10:30 PM   #9  
Unbelievable update! I took my Tahoe to the dealer. Prior to taking it there, I had AutoZone run a diagnostic and another independent business. Both of them said that the error code was U0102, failure to communicate with the transfer case control module. Once i get to the dealership, they tell me that it is the BCM and that it is going to cost me $520.00 out the door. I had no choice but to believe "the professionals" since I'm an active duty Marine and the Tahoe is my only mode of transportation.

So after being at the dealership for 6 hours, the service guy tells me that he needs another 2 days to figure out the problem. After they replaced the BCM, now they are getting 2 other error codes! WTF! Over! How can I take my 07 Tahoe with 60,000 miles, to "the experts" and it worse now after they replace the BCM than it was before i took it there? UNBELIEVABLE! There is a big difference between parts changers and mechanics! How is it possible to diagnose a vehicle, then give a quote to the customer and totally flip the script 6 hours later? And then have the ***** to try and charge me.

I KNOW TIMES ARE HARD THESE DAYS BUT DO YOU HAVE TO ROB YOUR CUSTOMERS? I prefer to keep running the Tahoe and completely ruin the damn thing before I get robbed!

 
Maxeymax's Avatar
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August 8th, 2015, 2:02 PM   #10  
I have this happening to the Two 2007 Tahoe's I have. Would never take an electrical problem to the Dealer. They replace and you pay. Have no solution now. will have to dig into the Google world for the answers.

 
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