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Old 07-19-2013, 09:45 PM   #1
Dachdu69C10
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Low tail light voltage and no lights

Hey guys I'm having issues with my tail lights, I made a new harness from the firewall to the lights themselves, I have 10v with the brakes applied at the firewall connector, and it goes from 10v to 3v with the blinkers on. All the wiring is done the way it would have been factory. And each brake light has a ground from the housing to the underside of the bed. I also have 10v at the bulb sockets and new bulbs but no light at all. Any suggestions?
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Old 07-19-2013, 09:54 PM   #2
cdowns
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Re: Low tail light voltage and no lights

run a ground wire from the bed to the frame to complete the circuit
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Old 07-19-2013, 10:01 PM   #3
chvtrkman
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Re: Low tail light voltage and no lights

Yup,what cdowns said...I had the same problem and it turned out the ground was bad. Ran a new ground wire directly to frame and problem solved.
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Old 07-19-2013, 10:13 PM   #4
CastIron
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Re: Low tail light voltage and no lights

I bet that if you measure voltage at your ground wires you'd have 10 volts there too. A system that was working properly should have zero volts after the bulb.
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Old 07-20-2013, 01:37 AM   #5
Dachdu69C10
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Re: Low tail light voltage and no lights

I ran a big 4 gauge ground from the chassis to the cab, and re ran the grounds from the housings to the frame. They are working better then ever thanks for the advice guys.
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Old 07-23-2013, 07:20 AM   #6
Square_78
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Re: Low tail light voltage and no lights

I've got the exact same prob. I went to install LED tail lights and they don't light up. Tested the voltage at the tail light socket and its like 9 volts. Not enough to trigger the LEDs. I am going to make a good ground strap and hopefully it makes a difference. Good info guys thanks
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