SVC 4WD coming on intermittantly

T_ClarkEx39 · June 24, 2018

2017 2500HD, 6.0 motor.

Not one issue out of this truck since i bought it new last July.

Then May 7, with 17K on the clock, the SVC 4WD soon light came on. Took to the dealer, and other than the codes being thrown, they couldnt figure out exactly what was causing it, kept it for the day, then told me to come get it and bring it back if it did it again.

May 21, it happened again, in addition to that, the SVC STABILITRACK came on as well. This time i drove it straight to dealer before the light went out (light goes out with ignition cycles).

They asked me to leave it with them the next morning (this was almost closing time when it happened) so i dropped it again the following day.

They STILL couldnt make it duplicate what was causing it, found a connector that was suspect for the transfer case control module, so they replaced the entire Aux Fuse Block Wiring Harness and cleared all codes and i picked it back up.

June 18, SVC 4WD light comes on again, so again, i take it back up to them, drop it off and they cant get it to duplicate after keep it for 3 days starting it several times a day, so they call GM who tells them to replaced the two/four wheel drive actuator. They replace/clear codes and i pick it back up.

Now, this morning, 5 days later, it comes on AGAIN!!!!! WTF???

Anyone else experience this?? I love this truck, and this does absolutely nothing to the drive-ability of the truck other than when this comes on the information display, it will not shift to 4WD. Once i cycle the ignition, everything works fine again. I honestly dont want to fool with the "lemon law" if i dont have to, but this needs to be fixed, and i mean FIXED while it is under warranty. I'm frustrated and at a loss as what to do.

T_ClarkEx39 · June 25, 2018

Damn, no one?

Colossus · June 25, 2018

electrical gremlins. The most common issue on all vehicles in this day and age. What you are dealing with is not a common issue that has been reported on here, so you are on your own on this one. Eventually either you lemon it or they figure out the issue out of the process of elimination.

gearheadesw · June 26, 2018

Have you put it in 4 wheel drive? Does it work, go right into 4 wheel drive?

T_ClarkEx39 · June 26, 2018

When the light comes on, I tried to put it in 4-wheel drive and it will not engage. If I turn the vehicle off then turn it back on the four-wheel Drive will Engage like it is supposed to. This is something that's very intermittent.

Supreme Pizza · June 26, 2018

I would take it through an automatic car wash, that has "under body" spray / wash. Basically soak the entire 4x4 system with water. If its a wiring issue, that may cause the problem to be more consistent and thus easier to find. You may also want to find some really bumpy train tracks, speed bumpers, or a strip of those white "road turtles", to drive over. Jarring the suspension and axles may cause any wiring issues or sensors to either work properly or fail completely.

gearheadesw · June 26, 2018

Kind of sounds like a sensor going bad, as soon as it doesn't get a signal it trips the light. Wont engage because it's not sensing the transfer case? Or the axle movement?

revrnd · June 30, 2018

The issue I had w/ my GMT900 was that internally in the T/C a sensor failed giving me the service 4x4 alert, no stabilitrac, traction control or cruise control either.

Apparently the dealer service dept cleaned the sensor, and 'opened' the parameters of the sensor.

sk · July 3, 2018

This is a known issue on 1500's but I don't think many 2500's have it happen. Search the forums for things like "g218 ground", "pit5405" and "electrical issues - fixed" and you will find a bunch of threads about it. One of the threads has that PIT bulletin attached. Take that to your dealer and make them check everything listed in the PIT.

T_ClarkEx39 · July 12, 2018

damned if i can find ANYTHING that tells me just what PIT stands for? I mean, i know TSB stands for Technical Service Bulletin, but PIT?????????? Even my dealer doesnt know.

Colossus · July 14, 2018

https://www.abbreviations.com/PIT

T_ClarkEx39 · July 14, 2018

Seriously????

newdude · July 17, 2018

On ‎7‎/‎11‎/‎2018 at 8:51 PM, T_ClarkEx39 said:

damned if i can find ANYTHING that tells me just what PIT stands for? I mean, i know TSB stands for Technical Service Bulletin, but PIT?????????? Even my dealer doesnt know.

GM slang for "Preliminary Information," or PI. T/C/P/E are sometimes used after the "PI" to designate "Truck", "Car", "Powertrain", "Engineering Information", etc. So as an example, in GM Service Information (dealer access only): #PIT5251C: EZ Lower Tailgate Opens Too Quickly / Additional Effort To Close. "Preliminary Information Truck (PIT) 5251 (PI number) C (revision)."

PI's are not a TSB, but PI's are GM's way of documenting issues they have found in the field, and are either used to be an aid or hint to solving a vehicle's issue, or are a working stepping stone that lead to a service bulletin. A lot of what PI's present is based on information gathered from their dealer network, via the men and women that fix and sell GM vehicles. Worst case, Engineering requests, PI's and TSBs can lead to recalls, special policies, etc.

On any of your paperwork, did the dealer mention any DTCs that were found? You don't get those warnings typically without the truck capturing a failure and setting a code.

Edited July 17, 2018 by newdude

Stephanie · November 16, 2018

Did you ever get resolution on this? Mine just started doing the very same thing. 4wd works fine as long as that service light isn't on. Light will come on when Im in 2wd randomly. Dealer says they need light on to pull code, but I never know when it is going to be on and it resets with ignition. If I'm using 4wd when light comes on it drops down to 2 and wont go back to 4 w/o restarting it. I'm not about to let them just start replacing random parts they "think" it might be ?

T_ClarkEx39 · November 16, 2018

4 hours ago, Stephanie said:

Did you ever get resolution on this? Mine just started doing the very same thing. 4wd works fine as long as that service light isn't on. Light will come on when Im in 2wd randomly. Dealer says they need light on to pull code, but I never know when it is going to be on and it resets with ignition. If I'm using 4wd when light comes on it drops down to 2 and wont go back to 4 w/o restarting it. I'm not about to let them just start replacing random parts they "think" it might be ?

nope. As a matter of fact, it went back to the dealer just 2 weeks ago for the same thing. At least i got 6000 miles between the last time it happened and this time. The one thing about it happening this time tho (service 4wd and stabilitrac as well as cruise control not working), is that THIS time, it came on everytime i cranked up the truck. I could "dismiss" it, turn off the truck, turn it back on and it popped up again. I "thought" this was a good thing, because my dealer told me the same thing yours did, it needed to be happening constantly for them to see the code actually appear in order to figure out the problem. Well, AGAIN, they cant figure it out. They cleared the codes, pulled apart the connector that supposedly controls that system, coated it with die-electric grease thinking it may be getting wet and sent me on my way. Again, this was time number SIX for the same problem.

That day, i contacted GM's lemon law division. They agreed that something was indeed wrong and asked me exactly what "I" wanted them to do. I told them this and in this order:

1. FIX MY TRUCK. I have no desire to go through the pain in the ass process of lemon law procedure, and if they could come up with a DEFINITIVE reason as to why this was happening and a DEFINITIVE fix for the problem, then i just want it fixed and be on my way.

2. Replace my truck with the EXACT same truck except a 2018 model. I bought this truck brand new with a full warranty and i would expect to get nothing less as a replacement.

3. Full refund of everything i paid for this truck (extended warranty, plus my trade in vehicle money) so i can go find my own new truck.

Since #1 is my first choice, and the problem has been attempted but no resolution from the SAME dealer (which has been in business for over 40 years and is one of the better chevy dealerships in ATL) six times, they asked that when this problem happens again, that i take it to another dealership for a "second opinion". I agreed to that, with the caveat that they only get ONE SHOT at finding and fixing the problem. If the 2nd dealership cant figure it out, then i at least have the lemon law process started and we can go from there.

As i said before, i love this truck. other than the crap fuel economy of the 6.0, its a fantastic vehicle, nicest truck ive ever owned and there wasnt another one like it within a 500 mile radius of me when i purchased it. Its just hard to find a 2500 "GAS" truck that isnt a fleet or "work" truck. This is an LT model and has MOST of the options an LTZ does minus a few items that i really didnt care to pay the big $$$ for extra. If it wasnt for this little nuisance bug, i would say this is the most dependable truck ive ever owned. Hell, From the day i left the dealership, it was 14 months before this happened, and it was the FIRST thing and only thing that i can complain about. There has been zero times back for warranty work till this.

VERY frustrating to say the least.