Service 4 Wheel Drive , Message Center

[bill2fat]

I have a 1999 GMC 1500 4x4 with Push Button 4WD. the message center indicates nothing at startup but sometimes after 1 minute, sometimes after 30 minutes, sometimes parked ideling, somtimes driving ,but almost always the "Service 4 Wheel Drive" message will appear. I have checked all oil levels in the system and every thing is in good working order. 4WD works perfectly and all push buttons work fine. It does not set a code and the dealership says they cannot diagnose the problem without a code.

[grasshopper]

I have a 1999 GMC 1500 4x4 with Push Button 4WD. the message center indicates nothing at startup but sometimes after 1 minute, sometimes after 30 minutes, sometimes parked ideling, somtimes driving ,but almost always the "Service 4 Wheel Drive" message will appear. I have checked all oil levels in the system and every thing is in good working order. 4WD works perfectly and all push buttons work fine. It does not set a code and the dealership says they cannot diagnose the problem without a code.

 

I had this problem on both of my 2000 GM trucks! Your problem is most likely the 4WD switch selection cluster. In the early years the hcircuit board would crack and set the "Service 4WD" message. The only way to get the code is to arrive at the dealership with the light on. Change the switch assembly yourself, it only takes 10 minutes and a small flat blade screwdriver.

 

I hope this helps.

 

Butch