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robert21
Active Member
United States
10 Posts |
 Posted - 03/15/2011 : 4:04:24 PM
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Hello,
2004 GMC medium duty C-7 series with CAT diesel engine and hydraulic brakes. This vehicle came in to us with both the Red " Brake " warning light and the Amber "ABS" warning lights on the dash lit up. We found some harness connectors unplugged at the sensors on the master cylinder and the brake booster, but reconnecting them did not change anything. We checked fuses under hood and behind the dash in front of the passenger seat, all in place and not open. ( The truck drives and stops o.k. - it was driven in to us !) We do not have a Tech II scanner to communicate with this system, nor can we get in with snap - on Modus or Solus or Launch scanners
we swapped the ABS control module from a known good truck to this one, the light went out on this truck when we drove it, and the ABS light came on in the "Donor" truck SOoooooooooo.... we figured a faulty module, ordered a new unit, installed ( does not have to be configured or "flashed" - we have done these before ) road tested, lights "off"
then ........
2 days later, we went to use truck and the lights are back "on" and do not go out when driven, brakes work ok and fluid level is good. ( It's ALWAYS an adventure, isn't it?)
anyway, no one in my area has a Tech II Except the GMC dealer,
has anyone run in to this problem? thank you for your time.
Bob C Skyview Service |
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busboy1988
Active Member
12 Posts |
Posted - 03/25/2011 : 2:13:07 PM
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| well, haven't had the issue on the exact same kind of vehicle but had similar experiance...had abs light that no matter what did we could not get to turn off for very long. Pulled and diagnosed codes, swapped sensors, swapped wires-nothing helped. Long story short..start tracing abs wiring. If there was extra harness the factory wound it up and zip-tied it to something to keep it out of the way. Problem we had is they zip tied it too tight, often kinking or pinching the wiring and it causes strange codes to surface. After cutting all zip ties, rolling wire into larger bundles and lightly zip tying cable back to vehicle the problems went away. Had this same issue on 3 different vehicles and this fixed all 3...worth a try. |
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2004 GMC C-7 ABS and Brake warning lights on
