I have this message appearing once in awhile. I went to AutoZone to have them scan it and it came up no codes. How can I find out what this means? Oh yeah, I have a 2000 Silverado 4x4.

 

Common problem is the 4X4 switch goes bad. I hear it is pretty common. Either fixing solder joints or replacing switch is the normal fix.

 

What switch are you talking about, the actual buttons you press to engage the 4x4 into 4 lo or 4 hi? How do you diagnose it?

 

i have had that for the last year, nothing to worry about.






just kidding, on my truck if you unplug any part of the system that light will come one. any sensor or actuator or switch. there are lots of things it could be.

 

I just had that come on in my 00 Z-71, that has 130k miles. I wonder if it is like the "change engine oil" light; just telling you to get a service done. Or is it a problem?

 

That message means there is a problem. autozone will not be able to scan for those codes, and at times there will be no codes stored. Need to get to a dealer to get it checked. Possible causes-stated above, the selector switch is common to fail, but it could also be the transfer case control module, or encoder motor. Those are two other common problems also. That particular light is easier to diagnose when it is on, since at times there will be no fault code stored unless it is currently failing.
Also, check all grounds, battery and engine grounds, they could interfere with the transfer case operation if loose or dirty.

 

This is a common problem on our vehicles. There are multiple related TSBs. Just had my switch replaced although I only had the Service 4WD message once last winter (during a snowstorm and I had no 4WD!). The GM scan tool did find a code in history. Each button on the switch has a different resistance and that is how the TCCM knows what you have selected (saves on wiring). The control was tested and one of the switches was out of spec.


I can recall TSBs for moisture in connectors, reprogramming the TCCM with the latest software, and faulty TCCMs. As mentioned, there are other possibilities as well.

It was nice to have a problem that couldn't be blamed on the blower so I at least got some use out of my GM warranty.

 

Thats what I thought at first. I guess I'll bring it into the stealership. Can anybody post the TSBs?

 

take your 4WD switch out. take it apart. grab a solder gun and some solder. resolder each spot inside the switch. reinstall switch. never have a problem again.

 

ohyea, and mine has 134k miles.