Four wheel drive light is on

Tiny
JEREMY HEAPS
  • MEMBER
  • 2003 GMC ENVOY
  • 4.6L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 205,000 MILES
It won’t back up very good in reverse and it’s in 2hi most of the time. We rarely have in 4hi or low. It goes forward ok but my wife just backed it out of the garage and pulled it back in. We didn’t want to do anymore damage to it. We’ve never seen this light come on before. Is this something that can be fixed on our own or does it have to be brought in to get diagnosed first?
Tuesday, April 21st, 2020 AT 2:16 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,776 POSTS
Hi,

It sounds like the vehicle is locked in 4wd. You indicated that you never saw the light in the past. Is it different than the 4wd indicator light when in 4wd? Have you tried switching to 4wd and then back to 2wd? Did this happen all at once?

Let me know.
Joe
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Tuesday, April 21st, 2020 AT 5:19 PM
Tiny
JEREMY HEAPS
  • MEMBER
  • 2 POSTS
Hi Joe.

Thank you for replying. So, when my wife started the car up the light was already on. She just backed up out of the garage and noticed the light was on and told me about it. There wasn’t much power to be able to back it up. I told her to put it in 4 hi and then back to 2 hi. Nothing changed. I just told her to drive it back into the garage and not to drive it until we figure out what’s going on. So, to answer your question, the light I’m referring to is the 4 wheel drive service light on the dash (similar to the check engine light and not the light that shows it’s in 4 wheel drive.) I know the light is on but other than that, how can I tell if it’s locked in four wheel drive?
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Wednesday, April 22nd, 2020 AT 2:32 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,776 POSTS
Hi,

If it is locked in 4wd, you will feel the steering fighting you when making turns on dry pavement. Also, the vehicle will fight itself when trying to move in a turn.

Since it is a service 4wd light, I have to recommend having the computer scanned for diagnostic trouble codes. That will point us in the right direction. Most parts stores will do if free of charge, but I realize it may not be safe to drive any distance.

See if you can get your hands on an OBD2 scanner. A parts store may lend or rent one to you,

Let me know,
Joe
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Wednesday, April 22nd, 2020 AT 4:43 PM

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