Four wheel drive service light

1999 GMC SUBURBAN
177,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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BIG DUTCHMEN
  • MEMBER
  • 3 POSTS
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
Feb 20, 2017 at 10:27 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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STEVE W.
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 15,146 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.
Feb 20, 2017 at 11:38 AM
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