Why does my tail light fuse blow ?

2007 Base w/2.7

I added a frame hitch and a plug-into the connectors light kit for the trailer light plug. Periodically the tail lights stop working and each time the fuse is blown.

I searched for electrical shorts physically and also with a meter and found nothing. So then I replaced everything electrical on the trailer with a new light kit: lights, wiring harness, and plug. Still the tail light fuse eventually blows out and I am left with no tail lights. It doesn't happen immediately - but always within one short trip somewhere.

Later I eliminated the side maker lights - leaving only the two tail lights as the electric loading for the circuit. With the same result - the tail light fuse in the truck eventually blows.

The original fuse was 10 amp. Last night in annoyance I installed a 15 amp fuse instead. Now over-fusing a wire does not appeal to me but what is the option? Installing a tail light relay? <g> Maybe installing LED trailer lights? <g>

Can the original 10 amp fuse really be That Close to the actual amp draw? <g>

What is the Real Answer?

Thanks.

PHM
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You have a short somewhere (probably when installing trailer hitch wiring)
Putting bigger fuse can make things worse and more expensive to repair. If you fry that harness going to the back of the truck, you are going to be looking at big $$$ repair.
Find a short and fixed or disconnect wiring you put in completely.

 

By any chance do you know the resistance of the lights?

 

Because it needed the money!

 

AHHHH, Dice!

 

Some thing in the range ohms 12 ohms when lit. A non power bulb will probably some thing closer to 2 ohms.

 

Probably no more that 2-3 amps tops you got some thing pinched some where.

 

It could be as simple as ground touching power.

 

Any resistance under 1.2 ohms will cause a 10 amp fuse to blow. I would measure the resistance when the lights are not lit and go from there.

 

First you might try the bulb alone and see what its resistance is. Due to the fact it is intermittent hooking a meter to it probably won't do any good. A one ohm resistor will not blow a fuse it is a common value for old ballast resistors. OP it's going to be a seek and destroy mission you may have to sacrifice a few 10 amp fuses plug it in and start pulling on trailer wires my camper has 10 parking/tail lights and does not blow fuses.