Low Voltage on Dome Light / Dimmer Circuit? - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 2 Old 07-11-2016, 10:15 AM Thread Starter
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Low Voltage on Dome Light / Dimmer Circuit?

I was installing some LED footwell / bed lights. I made the lights myself using some SMDs that I weatherproofed. Anyway ...

When I originally probed the dome light wire, I was pulling about 7.8V when the lights were off and about 12.9V when the dimmer switch on the column was set to "ON".

I spliced into the dome light circuit to power the lights, and began wiring up the lights. Once I had two of six strands of lights installed, I decided to test the setup. I turned the dimmer switch on, and the lights lit up. However, I had an issue with one of my solder joints, and the lights went out.

I fixed the bad joint, and have tested each strand of lights to ensure all are OK. All strands work when powered from a bench supply operating at 12V. However, when I try and power off of the dome light circuit now, the lights do not come on.

Now when I probe the dome light circuit, I get about 3.7V when the dimmer switch on the column is set to "ON". This is obviously why the lights do not come on any more, but the question is ... What is the cause of the low voltage on the dimmer switch circuit now?

Is there a protection function of the CANBUS that I am encountering?

As an electrical engineer, I am a bit confused as to why this would be happening.

Thanks mucho for the help...

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post #2 of 2 Old 02-25-2018, 12:11 PM
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Just curious if you found a solution, have had issues with my 12 jk dome lights. With no load, and switch on, i get 12 volts, hook a small led light to ii and voltage drops to @7, won’t even light an incadesent bulb, so I too am wondering now if there is some kind of protection in the circuit
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