4 Wheel Service

Is it on all the time? How long has it been going on?

I'v got a 2000 Silverado 4x4 with about 125,000 on it. It started doing the same thing but only on long highway trips (2 hrs or more)...anyone know what causes this?

As I understand it, the service 4wd light is analagous to the service engine soon light. It basically means that the 4wd computer has detected some fault. The 1st diagnostic step would be to hook it up to an appropriate scanner and "ask" the 4wd computer what fault it has seen and go from there.

Can you hook it up to ones they have at Advance Auto Parts or Autozone that they do for free of do you have to take it to the dealership and hook up to one of theirs?

I do not believe the engine scanners that places like autozone would use are able to talk to the 4wd computer.

I googled it the other day and alot of people are saying that it usually is the
4WD selector switch on the dash and its only about $60 from the dealership. If you want to go off you can try disconnecting the battery for about 20-30 min. and it should reset it.

Typically it is the 4WD switch.....but there are also some issues with the encoder motor/sensor.