10 amp TAIL fuse keeps blowing when I turn on the lights

Hola... 2018 Sr5 5.7

the 10 amp fuse under the steering wheel marked TAIL keeps blowing out every time i switch on the lights.. my running lights are out.. blinker, head lights, brake lights, license plate,dashboard, everything else seems to be working just the tail running lights are not on... I checked the bulbs they look fine,, swapped out the relay for one that works and it still blew a fuse.. i thought it was from when i hooked my boat up a few days back but now im not sure as it still keeps blowing without the trailer hooked up... Ive checked all the fuses in both boxes that sound related to towing or lights and they all seem fine... Whos a genius here????

 

unhook the harness from the rear bumper and try turning on your lights. You may have a loose / exposed ground somewhere which will trigger a fuse to blow.

 

fist off thanks for the help.. i tried unhooking the harness going to trailer light plug and then put in a new fuse, turned on lights and it blew.. is that the harness or is there another harness you’re referring too??

 

Yes, that one, then I would revert to an exposed ground somewhere in the harness, which may require some digging. You can also check the grounds out of the fuse box which are located just behind the driver side head light, mine came loose for whatever reason and would blow out my head lights... Also check the grounding points under the kick panel and ensure those ground are tight and dry.
Long ago, my car's fog lights had an exposed ground wire and it would blow out the fuse every evening when the lights popped on, or when I turned the light switch...

 

phew never easy.. thanks again for the advice i’ll start digging .. good karma for ya

 

Mine did the same thing when i installed my NSV headlight patch harness .... but just fixed mine 2 hrs ago ... hope she holds up.

 

If you can't figure out where the short is coming from, consider switching to a circuit breaker instead of a fuse. They make little circuit breakers that can fit into where the fuse goes, and they automatically reset. You'll want a Type I breaker for this. They'll be a lot longer than a regular fuse, but should still fit. The circuit breakers I used was just short enough to put inside the passenger side kick panel with the panel door closed on my Honda Odyssey. Bad usb/power cables kept blowing fuses on the 12v outlets.

Example: https://www.littelfuse.com/products...uit-breakers/30418-mini-circuit-breakers.aspx
Type I, II, and III explanation: http://info.waytekwire.com/blog/a-basic-guide-to-circuit-breaker-types

You can buy unbranded ones on Amazon such as "T Tocas DC 14V 5PCS Auto-Reset ATM Mini Blade-Style Circuit Breaker (10A)"

Still won't fix your issue, but if your tail lights are only intermittent it would help.

 

Its a cool idea but unfortunately if your truck has a DEAD SHORT even if you put a 200 amp breaker on it .. its just a band aid .. it will still pop .... need to trace and back track whatever you tapped to the parking light and simply put it back to factory set up.

 

Mine started doing this the other day, we're on the road for another week so I'll look at it when I get home. Not driving at night any time soon. The only change I made to it was the installation of Winjet tail lights before we left.
Changed the fuse with a 15a because its all I had, popped right away, should be easy to figure out when I get time.

 

Good luck, might be those resistors pack that comes with the taillight.

 

Warranty? It's a 2018 so depending on mileage you might not have to deal with this and let a tech get frustrated instead

 

Not with a 15a fuse. lol

 

Replacing a 10 amp fuse with a 15 can lead to a catastrophe. It probably won’t start a fire but it is possible. More likely it will damage a wiring harness that will have to be replaced. That’s not a cheap job. They put a 10 amp fuse in that circuit for a reason.

 

So... is everything on your truck stock? I ask because people have these problems, then later they mention they wired in a lightbar, switched to aftermarket led bulbs, etc etc. might help us help you.

good luck!

ryan

 

We just look at things differently, my experience tells me its not a big deal though I appreciate the heads up.
I've built wiring harness's from scratch for several vehicles so I have a solid understanding of whats going on and the risks involved.

 

Fair enough. You do you. My concern was there are probably a lot of folks on this board who have no education, training, or experience on electrical theory/issues. The way you stated things in your post could lead some of them to end up putting a 30 amp fuse where it should be 10. I have witnessed catastrophic results from similar actions. Just trying to keep someone from making a terrible mistake. I meant no offense.

 

To be clear, I didn't say anything about a 30a fuse in place of a 10a. At 10a its a circuit that sees 6-7a max, nothing catastrophic is going to happen by putting a 15a fuse in that circuit, in my experience.
Although it is 2020 so who knows. No offense taken at all, we should be able to have a civil discussion even when we disagree.

 

A shorted ground will not blow a fuse, that’s what grounds do. If a ground in that circuit was shorted to the positive wire yes. A loose ground normally dim light. Never use a higher amp fuse. If no aftermarket lights I would take to dealer if you still are in warranty.