brake lights

1998 GMC SIERRA
190,000 MILES • V8 • 2WD • AUTOMATIC
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BJ149
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  • 1 POST
I CHANGED THE MOTOR AND TRANSMISSION IN MY 1998 GMC SIERRA 1500 AND NOW WHEN I TURN THE KEY ON THE BRAKE LIGHTS COME ON. WITH THE KEY ON IF I PRESS THE BRAKE PEDAL THE LIGHTS GO OFF. WHAT COULD BE THE PROBLEM?
Mar 18, 2011 at 8:52 PM
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RIVERMIKERAT
  • ✓Experienced Mechanic
  • 6,106 POSTS
Brake lights or running/tail lights? Check under the dash for pinched wires coming from the brake light switch.

Check for shorts in the harness with a multimeter. Disconnect the battery and remove the brake light bulbs. Probe one contact in the brake bulb pigtail and go to ground with other probe. Resistance should be infinite. If not, you will need to trace the wires and find where the short is.
Jun 18, 2011 at 3:38 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
Is the high mount brake lite coming on too? If not unplug the turn and hazard switch and see what happens to the lite
Jun 18, 2011 at 3:56 PM
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