Four wheel drive service light

Tiny
BIG DUTCHMEN
  • MEMBER
  • 1999 GMC SUBURBAN
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 177,000 MILES
I have the four wheel drive service light on in the instrument panel. I replaced the four button switch, and the actuator. After it is driven for five to ten miles the light comes on and it kicks it from four wheel to two wheel drive and the light comes on in the dash.
I am wondering if it is the TCCM or is there other things that can cause this. My local service guy says you can not pull a code the regular way. Is there some how to test the TCCM?
Thanks
Monday, February 20th, 2017 AT 10:27 AM

1 Reply

Tiny
STEVE W.
  • MECHANIC
  • 12,995 POSTS
If it has any codes (which it should with the way it is acting) you need a dealer level scan tool that can read them and allow you to test the TCCM operating modes. Some aftermarket units can read the codes, but many times you need a new module and programming to get it working.
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Monday, February 20th, 2017 AT 11:38 AM

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