Service 4x4 light

[NealM68]

My service 4x4 light comes on occasionally (1 out of 10 times) for a few seconds when I start my truck. Does anyone know what might cause this? I brought it in to the dealer twice and they didn't get any codes from it. I'm about 3000 miles from the end of my warranty so if it potentially serious I'd like to get it fixed ASAP.

[Spartus]

There is a service bulletin on this... Mine was getting a LOSS OF COMMUNICATION fault between the 4wd and the computer.. They replaced the 4x4 selector switch and some solenoid in the transfer case. Problem solved....

[NealM68]

Did your light stay on? Mine comes on for a second or two and goes out. I haven't had any driveability problems and 4x4 seems to work fine although I rarely use it. Thanks for the service bullitin info.

[FisHn2DMax]

If you haven't had the updated TSB for the push button 4x4 selector, you probably should! Mine started with the light staying on (erratic) and then finally a "Service 4 wheel drive message" on the DIC. I got the encoder TSB update and the problem is gone. Get it done before the warranty expires.

[jbplock]

Originally posted by FisHn2DMax:
If you haven't had the updated TSB for the push button 4x4 selector, you probably should! Mine started with the light staying on (erratic) and then finally a "Service 4 wheel drive message" on the DIC. I got the encoder TSB update and the problem is gone. Get it done before the warranty expires. Dittos ...Mine was the same way... It will most likely get worse. The risk is that it may get stuck in 4W-HI or worse 4W-LO. There is a fuse you can pull to prevent the 4WD from engaging until it's fixed. The dealer who did mine says they ignore the GM recomendation to R&R the encoder and just replace the whole motor assy. They have had them come back if they don't. The service writer also said that the encoder motor assy has a label on it that indicates it's not a servicable part. He said they also have trouble with the 2WD/4WD selector switch. smile.gif

[roadrat68]

I had close to the same problem but my transfer. was locking in 4 wheel low on me some times the light would come on. the dealer replaced my switch and Encoder motor on the tranny. Aperantly the encoder motor works off of diffrent voltages going only throu 3 or 4 wires to select the diffrent ranges in the tranfer if your switch or encoder is bad it will toss out codes. :D