If your 4wd is push button like most are these days then most likely it is a switch or possibly the encoder motor.Just had my encoder motor reprogrammed in my truck in march and its being replaced next week.I suggest pulling your battery for 30 mins or so before anything else as this will reset the comp and with luck will resolve your issue
you need to service your 4wd. It means that the computer that controls the 4wd has detected a problem and set a code. You will need to have the system checked with a scan tool.
re: 04 Envoy - my service 4wd light came on in the middle of a 10" blizzard. I researched it and took it to Jiffy Lube and had the front & read differential fluids changed. Light went off and has stayed off. Now my "service engine" light keeps coming on - I'm concerned that I may have a crack in the gas tank as I have read many many other Envoy owners have experienced.
It means your screwed. Got a 2007 myself and can not figure it out.
The computer that controls the 4wd has detected a problem and set a trouble code.
that 4wd is engaged and working if it blinks there is a problem with the 4wd
I had my 200 blazer scanned an was told it was a bad fuel tank cap. I replaced it and the light is still on.
My 2005 Chevy 4wd, ext. cab,shrt bed, has push buttons to go from(from top to bottom) Auto 4wheel drive, to 2 High , then to N(neutral), and then to 4 high, then to 4 low. At approx. 50,000 mi. the service indicator light came on and indicated "Service 4wd." I re-set the indicator, and forgot about it. Now, at 63,000 mi. it's telling me to service the 4wd, only this time the reset works until I turn the ignition off. when I restart, the service light comes on. However, the indicator lights that show which gear the transfer case is in, does not light up, and there is no automatic shifting of the transfer case. Is there a simple solution to this problem? Recommendations...Please! popo63
Sounds as though you have a faulty gear box.
check the alternator and battery.
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The 4WD Warning Light appears as the characters 4WD with an exclamation mark, and indicates a fault with your 4WD system. If it's blinking repeatedly, the system is completely disabled due to an overload.
Repair Rear Differential Parts