View Full Version : Weird wiring issue with license plate
Alex_V
08-23-2022, 08:57 AM
I have to admit, I am puzzled. Here is the scoop.
When I turn on the running lights, first click on the light lever, the 15a fuse gets blown. If I unplug the license plate lights everything is fine, fuse is good. So there is some kind of issue with license plate lights, right? Everything inside looks just fine. So I tried it without light bulbs, still pops the fuse. Ok, put a 20a fuse, still gets popped. I unplug the license plate lights and everything works as it should.
Any thoughts?
egchewy79
08-23-2022, 09:04 AM
first, not sure if putting a bigger amp fuse is the right idea. the wires are only rated for a certain amt and could lead to problems by just simply putting in a different fuse. sounds like you have a short somewhere in your license plate light wire. I'd pull the loom apart and start tracing it backwards in the harness.
Alex_V
08-23-2022, 09:08 AM
Yeah. I wasn’t happy trying the 20a fuse. Something in a brand new license plate is causing the fuse to blow. Visually everything looks fine. Wires coming out of it are just 12” long. Once unplugged fuse stays intact. Just weird.
Make sure you don't have power and ground touching each other anywhere. That includes any potential assembly defect in the actual fixture.
narly1
08-23-2022, 09:26 AM
Once unplugged fuse stays intact. Just weird.
OK, so by this very simple action you have isolated the issue to the wiring in the plate bracket. If the bracket has 2 wires one would be the +12V (hot) connection to the bulb and the other the return connection from the bulb. The return could be tied to the bracket metal frame and thus potentially connected to the vehicle frame/ground. In that case you'd have a short to ground.
Thus your issue might be as simple as having the two wires reversed.
Earl
boat737
08-23-2022, 09:29 AM
Disconnect the license plate light wiring from the system, both the 12v power and the ground. Remove the bulb. Put an Ohm meter on the two wires for the license plate light receptical. You SHOULD have an open circuit. If you have continuity (no resistance), there is a short, most likely in or near the bulb receptacle.. (with the bulb inserted, you WILL have continuity.). I suppose you could have some weird short IN the bulb itself, but that is very unlikely.
While this circuit is disconnected, you can check for normal 12 volts coming from the switch/power source as well.
Blitzboy54
08-23-2022, 10:09 AM
OK, so by this very simple action you have isolated the issue to the wiring in the plate bracket. If the bracket has 2 wires one would be the +12V (hot) connection to the bulb and the other the return connection from the bulb. The return could be tied to the bracket metal frame and thus potentially connected to the vehicle frame/ground. In that case you'd have a short to ground.
Thus your issue might be as simple as having the two wires reversed.
Earl
It could also be the wiring too the light bracket. I would also disconnect the light bracket and check the incoming 12v wire to ground. It should be open, if it is not there in lies your problem. But just like narly1 said this is simple problem that you have already surrounded.
Alex_V
08-23-2022, 02:52 PM
Found it, red wire had a spot with damaged insulation right where it goes through the hole into the trunk. Simple short. Now fixed.
narly1
08-23-2022, 04:06 PM
Found it, red wire had a spot with damaged insulation right where it goes through the hole into the trunk. Simple short. Now fixed.
I hope you put some sort of grommet in the hole before you put the wire back in. Time and vibration are big enemies of vehicle electrical wiring.
Earl