Strange Electrical Issues after modification to dome light circuit

Contento · January 30, 2018

I added running board and truck bed LEDs and followed a suggestion and directions posted here to tap into the dome light circuit so that when the interior dome light was on (lock, unlock and overhead switch), the LEDs would turn on. Worked perfectly (the part about the lights coming on and off correctly). However, I started experiencing some very unusual electrical issues that at first, I wrote off to a quirk. To start, the radio would not turn off after shutting the truck off, removing the key and opening the door. The radio would stay on for a few seconds sometimes then shut off. Sometimes for longer. Then sometimes not shut off at all. I came out of a store like 20 minutes later and the radio was still playing. Then, it progressed. When I would turn the truck on, the gauges would go a little haywire. They would bounce around (more than the normal initial sweep) and I'd get info center warnings for theft monitor, tire pressure monitor, and trailer monitor. They would all go away after beeping on and off a few times, and everything seemed fine (until I went to turn the truck off - the radio thing). I've also experienced a situation where the truck would start, but nothing in the dash would be lit (no gauges, no screens including the radio).

I took it to the dealership under warranty thinking there was something significant wrong, not thinking the modification to the dome light circuit could be the culprit. However, to avoid an issue where they would claim the modification was the cause and void the warranty, I undid the wiring modification. When I was describing the issue to the service tech, he said it sounds like a low voltage issue (like a bad battery or circuit), but the battery tested fine. They determined that I had a bad driver's door switch (ordered for replacement). I didn't reconnect the modification for a couple of days thinking that if I had to take it back to have the switch installed, I'd just have to undo it again. Funny thing, during that time I had no issues.

I reconnected the circuit modification and to no surprise, the issues returned.

Questions:

- would tapping into the dome light circuit in the circuit block under the dash (first block, grey wire I believe) causing this make sense? Are the LED's draw the culprit? seems to be confirmed through my testing.

- what are my other options? can I wire that mod to a relay that uses much less juice so that the circuit doesn't have issues with the draw.

- should I chose a different circuit? I saw a post that indicated the side mirror puddle lamps are in that BCM as well. That might be an option for the running board LEDs but I'd like the bed LEDs on a switch.

thanks all!

Sierra706 · January 30, 2018

If the draw is too high it could explain your problems. Try using a relay to power your lights, with the dome light circuit being your trigger.

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newdude · January 30, 2018

I'd go for the reverse lamp circuit or the cargo lamp circuit. Reverse lamp would give you the option to have them come on with your exit lighting, or if you went cargo lamp switch they would function just like the factory bed lighting.

ChevyRoofer · January 30, 2018

2 hours ago, newdude said:

I'd go for the reverse lamp circuit or the cargo lamp circuit. Reverse lamp would give you the option to have them come on with your exit lighting, or if you went cargo lamp switch they would function just like the factory bed lighting.

This is kind of off Topic/on Topic.

My reverse lights are currently out. Power won't get to them for some reason. Happen to have a drawing/some info on the reverse lamp circuit for myself and Contento?

adamj2121 · January 30, 2018

If you add a relay it should fix your problems. The running board lights are tied to the dome lights on my truck and I installed a relay day one and don't have any problems.

Contento · January 30, 2018

1 hour ago, adamj2121 said:

If you add a relay it should fix your problems. The running board lights are tied to the dome lights on my truck and I installed a relay day one and don't have any problems.

Thanks. What did you pull your hot from? Is there an easy spot under the dash there or do I need to go all the way to the battery?

adamj2121 · February 1, 2018

On 1/30/2018 at 5:50 PM, Contento said:

Thanks. What did you pull your hot from? Is there an easy spot under the dash there or do I need to go all the way to the battery?

I went to the battery with mine, I didn't really check for a hot under the dash, I wanted the relay to be in the engine compartment. No particular reason as to why, just what I wanted to do.

Contento · February 1, 2018

I finished wiring it up and it works BUT the relay buzzes like crazy when it turns on it off sometimes. Usually. I think it's possible it's the fading on the circuit that's causing it. The signal to the relay probably fades out, too causing it to buzz while it closes or opens. Likely? Solution?

adamj2121 · February 2, 2018

18 hours ago, Contento said:

I finished wiring it up and it works BUT the relay buzzes like crazy when it turns on it off sometimes. Usually. I think it's possible it's the fading on the circuit that's causing it. The signal to the relay probably fades out, too causing it to buzz while it closes or opens. Likely? Solution?

Forgot to mention this, I am used to the buzzing now, but it seems to be a problem with how the dome light circuit fades the lights out/in instead of immediately turning them off/on. I searched around on google for how to correct it and there are a few options, but I have never taken the time to do it. I have also read that some relays buzz and some do not.