Dingy Towing 2015 GMC Yukon 4WD

Finally able to post on GMC Forum but have yet to find email address for GM.

Diann

Clarification for Dinghy Towing 2015 GMC Yukon Denali XL (Keyless system and no EPB)

When we got our new vehicle we were given supplemental instructions on Dinghy Towing. For our vehicle this supplement replaces pages 10-78 thru 10-79 in the Owner’s Manual. As best as I can determine the only difference has to do with ‘Disconnecting the Towed Vehicle’. Step 5 in the Owner’s Manual indicates Turn the ignition to ON/RUN position with the engine off. In the replacement instructions’ step 5 says Start the engine, then shift the transfer case out of N (Neutral) to Two-Wheel Drive High. See Four-Wheel Drive for directions on shifting out of N (Neutral).

HOWEVER, in the Owner’s Manual on page 9-38 (where our “Shifting Out of N” instructions are located) it indicates the ignition should be in ON/RUN with the engine off! After dinghy towing, should the engine be off or on to shift the transfer case out of N (Neutral)?
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On our first trial run we were able to shift transfer case into N (Neutral) but were unable to shift the transfer case out of N (Neutral) back to 2WD. After trying to get help unsuccessfully from your Customer Service 800 number, we decided to tow our vehicle to the nearest GMC dealership where finally, on our second trip with vehicle in tow, we were given another set of instructions (#PIP5217A) on how to dinghy tow. These instructions had a revised Step 5.
New Step 5. With the transmission in D (Drive), turn the ignition to ACC/ACCESSORY.
5.1. Shift transmission to P (Park) and turn ignition off.
5.2. Wait 30 seconds before proceeding to the next step.
5.3. Start the engine and shift transmission to D (Drive) verify that the transfer case is still in neutral.

These additional instructions also included how to reset the transfer case error code by removing the 30 amp TREC fuse. The removal and reinstallation of the fuse, allowed us to shift out of N (Neutral) successfully after having gotten the ‘Service 4WD’ message. Furthermore, using the new step 5.2. waiting 30 seconds we were able to shift transfer case into N (Neutral) and then eventually to shift out of N (Neutral) WITHOUT getting the ‘Service 4WD’ message or having to remove the 30 amp fuse.

My husband and I are both disappointed with GM for not providing clear and accurate instructions on dinghy towing. The bulletin #PIP5217A was issued August 21, 2014. We picked up our new car in January 2015! While we were given supplemental towing instructions these did not include the expanded step 5 which apparently is the key to avoiding the transfer case error code. Furthermore, once GM had identified there was an issue with vehicles setting a bogus error code in the transfer case control module, it would make sense to provide owners an update with the expanded instructions, as well as, instructions on how to reset the code or, at the very least, warn them that the ‘Service 4WD’ message and the transfer case stuck in Neutral were related and the error code would need to be cleared before the vehicle would shift from N (Neutral) to 2WD!

Having successfully towed a 2004 4WD Avalanche for years, we are disappointed with the procedure(s) required to tow the Yukon. The complicated and conflicting instructions located in two different sections are irritating. Finally to find out the instructions were not just confusing but incomplete and inadequate was beyond irritating. Our experience with the Customer Service number was inexcusable with the man repeatedly asking me “Why did you put the car in neutral?” This was after I explained exactly what we had done and why! This left us very dissatisfied with your ability to service customers professionally and resolve issues promptly.

While we do understand that not many customers dinghy tow, we specifically ordered this vehicle so we could dinghy tow. I also understand the first supplement applied to multiple vehicles so identifying specific page numbers replaced was not practical; however, it would have been helpful to have a small statement summarizing what steps in the procedure had changed. Then to discover in May 2015 that the supplemental instructions were incorrect and/or incomplete and this was known by GM as early as August 2014 seems inexcusable.

The difficulty in dealing with instructions located in two places in the original Owner’s Manual plus the first supplement and then having to scour around to obtain the final correct information in #PIP5217A has been a huge hassle. AND there is still the unresolved issue of whether the engine should be running or not when attempting to shift the transfer case from N (Neutral) back to 2WD.

It would be really nice to have a complete correct single set of instructions on how to dinghy tow, as well as, to disconnect after flat towing.

Diann

P.S. I am still trying to find a place on GM website to email the above. I refuse to waste a stamp on this! I also have been trying to post on the GMC forum without success. Will try again!

Lots of owners of 2015 GM 4wd with the same problem. I will not buy a 2015 GM truck until this problem is solved by GM.

Moisheh

One thing you may want to do is find opportunities to exercise the shift mechanism between high and low range. In my experience some transfer cases are tight when new and reluctant to shift ranges. Had a Toyota a couple of years ago just like that it was fiddly and reluctant to change gears until after some months and enough low range use to wear it in. After that it was fine.

In the older 4x4's with hand shifters you could feel the resistance, and it was easier to finesse the gears into place. With the electronics you just have to push the switch and hope the shift mechanism gets it done.

Problem Fixed!

We would never in a million years figured this out WITHOUT the #PIP5217A: Service 4 Wheel Drive Message After Flat/Dinghy Towing – (Aug 21, 2014). Note the date! It even says that customers will be sent updated information (steps 5.1 thru 5.4). Funny when we picked up the vehicle in January 2015 no mention was made of this ‘issue’ nor were we given these instructions and we were definitely not warned about the consequences of the transfer case setting a diagnostic code that would prevent getting back into 2WD.

Bottom line - If you get the Service 4WD message after towing and transfer case will not shift into 2WD you need to follow these instructions:
1. With the ignition in the RUN position and engine not running,
2. Open the hood and remove the 30 Amp TREC fuse in the under hood fuse block (in our 2015 GMC Yukon Denali XL it is on the driver’s side rear most fuse … it is pink and fat),
3. Reinstall the 30 amp fuse
4. Continue with “Shifting out of neutral” in the owner’s manual.
Note: Removing the TREC fuse with the key on may cause additional messages to appear on the DIC including service stabilitrak. After the transfer case is shifted out of neutral turn the vehicle off, restart the vehicle and those messages should not reappear.

Also I will tell you that the dealership and we were successful getting transfer case to 2WD WITHOUT the engine running after removing and reinserting the 30 amp fuse.

I am trying to merge the 3 sets of instructions so that we will have a clear set of instructions on one page! I neither recommend nor suggest what you do if you experience a similar problem but we thought it was appropriate to share our own experience.

Diann

P.S. I can't figure out a simple way to attach scanned pages. Will try later when I am less tired. After we got home I turned on A/C units and a horrible noise began. It was the infamous dirt dobber nests. I had to crawl on top and take off top of A/C units (where I cracked the plastic on one of the screw holes) and dig out nests and clean debris. This should be an easy fix but I am old with two artificial knees and Robert is recovering from hip replacement surgery. Not asking for sympathy but just explaining why even simple tasks can be difficult and time consuming. Still I woke up this morning without dirt on my face and intend to do the same thing tomorrow. LOL

Thanks ... I just got off the GMC forum and found a reference to a technical bulletin that says to 'reflash' the transfer case. Have no idea what this means but we are headed to dealership tomorrow at 8 am. Hopefully they will get it 'fixed'.

Diann

When I put our 2005 Chevy Colorado transfer case back into 2 wheel drive from neutral I always have the engine off, ignition on. Then it sometimes takes several minutes of holding the button before it goes into gear. As far as the reset leave the battery off for 5 minutes or more before hooking it back up.
Good Luck!