No brake lights or DRLs!
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Joined: Nov 2021
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No brake lights or DRLs!
My brake lights and rear running lights are not working. A few days ago, I blew a fuse because of wires in my bed getting pinched. I replaced the fuse and fixed the wires. Everything works except the brake lights when DRLs are on and rear running lights. Blinkers, front headlights, cab lights, dash lights, and license plate light all work. My DRLs are also flashing with my blinkers.
I tested the voltage on the 4 pins of the taillights. Getting 12v on the first 3 pins and 0 on the ground pin. I tested for continuity on the pins of the taillight board and 1-3 all have continuity with bulbs installed. Without bulbs installed no continuity. With bulbs installed 1-3 have continuity to the ground pin. I also tested continuity to the harness ground pin to the ground on the bed and it was fine. I also have swapped the bulbs to make sure that they were not an issue as well as the taillight board that they plug into. This leads me to believe that the ground and bulbs are fine and not an issue.
Tested the brake pedal switch. Not sure which wires goes where but 12v on orange constantly and 12v on white when the brake is pressed. Brake lights work when park light switch is off.
I tested the park light switch and it is functioning correctly. 12v coming in and 12v coming out.
So to recap this post. The brake switch works, the park light switch in the dash works, the bulbs and circuit boards work, and my ground connection at the light is fine. Does anyone have a one-line diagram for this circuit? Trying to trace out where the wire goes after the switch is a nightmare. I am out of ideas for things to test. Any suggestions help!
I tested the voltage on the 4 pins of the taillights. Getting 12v on the first 3 pins and 0 on the ground pin. I tested for continuity on the pins of the taillight board and 1-3 all have continuity with bulbs installed. Without bulbs installed no continuity. With bulbs installed 1-3 have continuity to the ground pin. I also tested continuity to the harness ground pin to the ground on the bed and it was fine. I also have swapped the bulbs to make sure that they were not an issue as well as the taillight board that they plug into. This leads me to believe that the ground and bulbs are fine and not an issue.
Tested the brake pedal switch. Not sure which wires goes where but 12v on orange constantly and 12v on white when the brake is pressed. Brake lights work when park light switch is off.
I tested the park light switch and it is functioning correctly. 12v coming in and 12v coming out.
So to recap this post. The brake switch works, the park light switch in the dash works, the bulbs and circuit boards work, and my ground connection at the light is fine. Does anyone have a one-line diagram for this circuit? Trying to trace out where the wire goes after the switch is a nightmare. I am out of ideas for things to test. Any suggestions help!
Last edited by spookybz; Nov 10, 2021 at 7:20 PM.
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Joined: Jun 2018
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From: Utah, USA
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