Service 4wd light

[Eric Wettschreck]

This is neighbors rig. 99 Tahoe, 5.7, 240k miles.

His service 4wd light keeps coming on and we don't know why. I put my auto x-ray code reader on it and I'm not getting a code. Granted, this isn't the greatest code reader on the planet.

It goes into 4wd just fine. Coming out it takes a couple seconds but it comes out of 4wd. He recently changed trans and transfer case fluid and that didn't make the light go away.

Any ideas where to start looking?

[Macgyver55]

There are a few things but my first thought would be the shift encoder motor on the transfer case is weak or binding. I think that if they use 4wd only rarely, the shaft that they mount on can bind and slow the motor down. Supposedly they can be freed up by working it with a hand wrench with the motor removed. Another possibility which I just ran into recently, was the front axle actuator. This one was the opposite of your case where it went into 4wd slowly but came out ok. The other thing could be the dash switch. I'm not sure of the years but they did have a problem with them on certain years, though I think it was more recent than 99.

[Scott K]

Hey Eric, I just got your message this morning. Usually I find a bad 4wd switch, selector switch in the dash, when you get that message.

[Eric Wettschreck]

Thanks guys. I'll let the neighbor fellow know. Scott, I was kind of thinking you might be on your way back from LOW so broken cars are not the priority.

[MontanaMax]

I have a 2003 Burb (200K+). When the dash switch is going it starts lighting up the red neutral light and you have trouble getting it to switch from 4wd to 2wd or 4-lo, and it often switches on its own from ignition off to next on. When the service 4wd light goes on it's always been the front actuator on the transfer case. Not an expensive repair.

[walt501]

Click the link, it may provide you with additional information on repairing this truck.

Click Here

[Eric Wettschreck]

Replacing the switch did the trick. Thanks guys.