1990 Sierra

Tiny
CCARR71
  • MEMBER
  • 1990 GMC SIERRA
  • V8
  • 4WD
  • AUTOMATIC
  • 189,000 MILES
I am having problems with my tail lights. When my headlights are on I have nothing. When they are on you can just barely see the brake lights, and the turn sigals both blink at the same time.
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Wednesday, February 16th, 2011 AT 4:20 PM

1 Reply

Tiny
JDL
  • EXPERT
For the tail lamps, the brown wire is voltage, goes hot when you turn on the headlamp switch. Use a digital multimeter between brown wire and vehicle ground/metal part. You either have to backprobe the brown wire connector or penetrate the insulation on the brown wire, headlamp switch on, What is the reading?

Also, black wire is ground, if there is much voltage on the black wire, the ground is faulty.
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Wednesday, February 16th, 2011 AT 5:45 PM

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