Door lock thermal trip energizing the entire electronics tray to 12v?

So here’s a weird one: I Dynamatted much of the interior, including under the electronics trays. While working back there today I saw some sparks between the tray and the Dynamat (which has a thin metal layer). I checked and the tray has 12v (once you get past the black paint), which seems bad. I finally traced this to the thermal trip for the doors. If I unplug the brown wire, the tray is no longer 12v, and is properly neither 12v or ground.

It’s very weird. I assume this isn’t normal. Has anyone seen this before? Maybe the paint under the thermal trip has worn away and it’s making contact or something? Should the entire socket be 12v, not just the contacts?

For now I’ll just unplug my locks (I don’t lock the car anyway), but I would like to fix it.

Thanks!

— Joe

You should not have any "stray" 12 volts on the metal. You should figure out how it is getting from the CB to the metal. Check the terminals on the CB. Maybe something is touching or the CB is bad. Actually all metal should ideally be connected to ground. That way any stray voltage will trip a fuse or a CB.

Probably a faulty circuit breaker. Pull the load side just to make sure it's not connected elsewhere. Another owner had 12 volts on his metal plate and that was due to a faulty AUX relay.

I do have some other stuff running off the breaker, but when I disconnected those there was still 12v to the tray, so it wasn’t that stuff. Nothing is touching the terminals that shouldn’t be. I definitely would have expected the tray to at least be grounded, so I was a bit surprised that it was neither.

Ive since tried plugging the brown wire back in and testing again, and there was no rogue 12v to be seen. That’s a bit disturbing. I’m wondering if I should replace the breaker or the aux relay anyway, just to be sure. I think they’re both original.

Thanks!

— Joe

Given that the thermal trip breaker has a metal case, I’d say something inside was touching the shell. I’d just replace the breaker for peace of mind.


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Quote:

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Originally Posted by DMC5180

Given that the thermal trip breaker has a metal case, I’d say something inside was touching the shell. I’d just replace the breaker for peace of mind.


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Agreed with dennis!