Service 4X4 on screen 2005 Chevy Tahoe

[j cAT]

Originally Posted by girl in need

I' m having these same problems. the service 4 wheel drive came on a few months ago and only comes on now when on long trips.... now the stabilitytrac system disabled was on. It was in 4 wheel drive so i switched it back to 2 wheel drive. is it unsafe to drive it like this?

these vehicles ARE NOT TO BE USED IN 4WD ON SOLID DRY PAVEMENT !

If you have been operating in ANY 4wd position on solid dry pavement , I suspect that your drivetrain must be serviced immediately..

good chance parts/fluids are worn damaged..

[girl in need]

I didn't put it in four wheel drive it kicked its self into 4 wheel drive. Is it going to cost a lot of money?

[j cAT]

Originally Posted by girl in need

I didn't put it in four wheel drive it kicked its self into 4 wheel drive. Is it going to cost a lot of money?

you must explain better how this is working/not working.

example: as I drive my 4wd tahoe it goes into 4wd from 2wd by itself.

this happens how often ? what speed ? does it go back to 2wd when commanded ?

vehicle description, how many miles? last time 4wd serviced ? how long owned by you ?

you will need a drive train scanner to get the failure code. this requires a GM specific code reader. call for a shop that can read this. thenpost back with all your info. perhaps a simple fix. could also be expensive ..

[croqz71]

I have been having the same problems for about 8 months. The backlights work on the switches (4x4 and TC) They both are totally unresponsive. Service 4 Wheel Drive and Traction Control Disabled are always in my dash readout display. i had the codes tested by a GM technician with their laptop computer(newest version). There were no codes, however he was able to make the 2wd, 4hi, and 4low lights come on in the switch module (so I assume that means the switch is fine?). Now... should I just get the "encoder motor" or see if there is a program update or what? He said nothing about any new flash updates "reproggraming" for this. I need an expert answer. The encoder motor is around $250.00 now if I buy online. I should be able to install myself. I really want this fixed.

[j cAT]

Originally Posted by croqz71

I have been having the same problems for about 8 months. The backlights work on the switches (4x4 and TC) They both are totally unresponsive. Service 4 Wheel Drive and Traction Control Disabled are always in my dash readout display. i had the codes tested by a GM technician with their laptop computer(newest version). There were no codes, however he was able to make the 2wd, 4hi, and 4low lights come on in the switch module (so I assume that means the switch is fine?). Now... should I just get the "encoder motor" or see if there is a program update or what? He said nothing about any new flash updates "reproggraming" for this. I need an expert answer. The encoder motor is around $250.00 now if I buy online. I should be able to install myself. I really want this fixed.

the problem you have is a dealer tech unable or unwilling to give you the dtc drive train codes.

go to another repair shop that will give you these failure codes.

with the service 4wd Lt on this must have failure drive train codes..

then post back the dtc drive train codes ..with this the forum members will get you going in the right direction..

you have a componet failure not a need for any update !

[Lionel2]

Originally Posted by girl in need

I' m having these same problems. the service 4 wheel drive came on a few months ago and only comes on now when on long trips.... now the stabilitytrac system disabled was on. It was in 4 wheel drive so i switched it back to 2 wheel drive. is it unsafe to drive it like this?

Hi girl in need,
Service 4x4 ligth comes up on my Yukon 2005 also. Its been flashing for few months. Now, ramdomly car shift to 4x4 by itself while driving. I'm unable to control the transmision mode pushing on the panel 2wd, 4-lo, 4-hi switches. I have been searching and reading coments about this issue. Cause of problem are many. So far, the ultimate solution I found is to go the dealership for a computer/transmission software update before replacing any part and go from there. The new software should give you the right code of what is wrong.
Possible problems are: Low transfer case fluid or insuficient lubrication due to lack of use of 4x4, the panel switch/cluster itself, the 4x4 tranfer case relay, 4x4 control motor in front axel, wiring, or encoder sensor/motor (c0327 code).
I have not seen my stability (Cory_e talks about) or traction system disable light on. So, I hope the encoder is not my problem. And all the lights on the cluster swith ligth up and flash before stoping on the 2WD, so, I hope my problem is not this switch either. And I have not changed/serviced the 4x4 fluids ever. I now have 75K miles on this Yukon.

My research shows that these repairs cost about $800.
If not repaired soon, car could engage in 4x4, and a turn on pavement could damage gears and other parts. That happends to someone I know with a Chevy Z71 Silverado pick-up truck 2003 and the repairs were $2300.!!!

Good luck

[upthereinthesky]

Hi, Guys. Thanks a lot for all the great info. I just purchased a used 2005 Tahoe a week ago. The "Service 4WD" message appeared yesterday. No other messages appeared. I selected 4WD, and it went in OK. Just wouldn't come out! I drove around the yard a little bit, reversing direction and gear, and eventually it went back to 2WD. Subsequent attempts to re-engage 4WD failed. The 4WD (HI) button would flash for 15 seconds or so, then extinguish. Upon selecting 4WD, I heard noises down below as it attempted to satisfy the request. Now, when I select 4WD, either HI or Low, the indicator lights stay black and there's no activity. It's as though the computer had locked out the switch panel 4WD functions.

The Tahoe has 93,000 miles on it. It was a fleet owned vehicle. I'm not sure if that's a good thing or a bad thing. I assume it didn't go off road. The undercarriage is cleaner, corrosion-wise, than any of the Tahoes we looked at.

Monday, I'm going to take it in to get the Drive Train Diagnostic Codes read, and have them put it up on the lift and check out the transfer case fluid, then change it, and see what happens.

The used car dealer I bought it from is down in New Jersey, about an hour and forty-five minutes drive each way! He said I have to bring it in for servicing. By the time I do that, I'll be approaching the limits on my one-month, 1,000 mile warranty. Hmmm.

Plus, it's a real drag driving down there, we'd have to take a chase car along, leave the Tahoe there, come home, drive back down, etc., etc. etc. What to do?

[j cAT]

have the drive train failure codes read by a shop near you. report the findings here.

If its just the encoder bad then have that work done near home. see if the used car dealer will cover it. keep all paper work.

could be bad wiring. wiring is very fragile on these vehicles. the fuse box underhood wires to the transfercase get damaged very easily.

If the transfercase fluid is black then you should consider getting your money back/return the vehicle. cost can be quite high.

the encoder usually fails because the fluid is black/damaged. this stresses out the encoder. the black is clutch material which in most cases is from operating the vehicle in any 4wd setting on solid dry pavement , also tires of different wear or size . all tires need be worn and rotated to keep at the same size / wear.

[upthereinthesky]

JCat:

Thanks so much for your great advice! I'm going out to the car now. I'm going to see if Onstar can read the OBD.

The dealer says he can't trust anybody to not rip him off, so I must drive the vehicle down to Jersey. I wonder what he'd say if I told him I was stuck in 4 Lo??

[upthereinthesky]

OK. Onstar ran a diagnostic. Tahoe is experiencing a C0306: Motor A or B Circuit Malfunction. Service within 7 days.

So, not an immediate emergency. The operator handed me off to a diagnostic specialist who said it could be as simple as a loose wire, or possibly a bad TCCM.

Guess I'll call the dealer again and see what he'll do, or won't do.

[j cAT]

Originally Posted by upthereinthesky

OK. Onstar ran a diagnostic. Tahoe is experiencing a C0306: Motor A or B Circuit Malfunction. Service within 7 days.

So, not an immediate emergency. The operator handed me off to a diagnostic specialist who said it could be as simple as a loose wire, or possibly a bad TCCM.

Guess I'll call the dealer again and see what he'll do, or won't do.

the transfrcase encoder motor is the weak component. the electronic control module rarely fails. I would say is is the encoder. this can be checked by measuring for a short or open.

the next thing you must do is see what color the fluid is.

[j cAT]

should have been some other codes found.

[upthereinthesky]

Thanks very much.

Yes, you would expect a 309 if the encoder was bad. That's why I was a little relieved to see an electrical fault. Even if it was the TCCM at $700 a pop! At least the tc wasn't smoked in that event.

But now you've got me concerned. So tomorrow, I'll take it to the car wash and see what their reader says. Also, put it up on the lift and check the fluid, and change it. Although,iirc, they may not stock the special fluid.

Edit:

From the User's Manual:

Dexron®-III Automatic Transmission
Fluid. Look for “Approved for the
H-Specification” on the label.

So:
Wondering what to do if the fluid is fried. Leave it in the transfer case as evidence for the dealer to confirm?

Or: change it and risk his denial?

Thanks again!

[GMCustomerService]

upthereinthesky,
Is the dealership you're working with one of our dealerships? Let us know as we would be happy to look into this further.
Best,
Sarah
GM Customer Service

[upthereinthesky]

Sarah:

Thanks very much. This dealer is a small, privately owned business. I'm not sure how one would tell if it is a GM franchise. I assume this place is not, as they sell only used cars, and a hodge-podge at that. As a matter of fact, judging by the cars on their lot, they sell mostly Hondas and Toyotas.

Thanks again.