Helping a friend here, so I don't know all the details.


He's blowing the brake light fuse. (was nice of the cop to tell him brake lights were not working and not give him ticket for it)

From what I've seen in some of the other threads, it could be a relay issue, a rubbed wire by fuse box on fender or a rubbed wire on 3rd tail light.

Are there any other places for him to check?

I don't quite understand how a bad bulb would blow a fuse, but I saw that in there as well.

From what I understand, everything else works.

I know he's been having an issue with one of the blinker relays when its cold sometimes.
Is this related???

 

He says he put one in this morning and it worked fine most of the day then started blowing them again.

Sounds like a rubbing wire?

He says he has no bulb in the 3rd brake light either.

Where is the best place to start looking for a rubbed wire?


He says when the fuse goes it will bog the truck down for a second.

 

Turn signals and brake lights are the same bulb in the rear. If one popped the fuse, the other would too so that can help the direction you work.

There is the third brake light also. Wiring is different than rear lights.

Brake light switch in pedal area also.

If no meter to test with, put in new fuse and wiggle all the harnesses for the brake lights.... it this can cause other problems by grounding out the wires and causing burning.....

 

Oh, Okay, so that means its probably not a bulb issue then.

What do you mean?
The third brake light is on a different circuit?

Please be a bit more specific.
Yeah, he has no meter, and its over 2 hours to get there, I have to be down there sunday morning. Gotta get this fixed to leave to go to new york. ugh. Stuff always breaks before a trip. *sigh*

I told him to throw in a fuse and wiggle stuff.

Everything seems to be triggered with the pedal though, so it seems to be when the lights are being requested to turn on.

This really does sound like a short, Not really sure where it would be at besides on that mentioned place for the fender.

 

I do not have wiring diagram so I am using past experience.The third brake light should be wired right off the pedal switch....or it could be a switch on the master cylinder.....The rear brake lights should pass thru the turn signal switch because of using one bulb vs desperate bulbs.

Hard to trouble shoot when it takes time for it to blow the fuse. Removing bulbs and checking will most likely not help either.



Using a meter is the easiest method. Need to start at the brake light switch and follow the wiring from there.

Do the emergency flashers work ok? They use the same bulbs so there is more wiring tied into the system.

 

He says flashers are fine.

 

That would put the problem more towards the brake light switch I would think. That system also cancels the cruise control.......

 

He could also check the wiring for the trailer. Some people use vampire connectors on trailer wiring harness. The end of the plug if it has some type of cover might have water in it also. If water in connector then blow out with air or brake parts cleaner or I would use electrical cleaner spray. Simple check but can be aggravating with the water in it.

 

He actually thought of that one over the phone. I wasn't sure if it would do it. I hope that is the issue. Cause 8 hour drive to new york on sunday... yeah.

Poor truck needs a bit of love, they were a bit rough on it before he got it.

He's spending some time to get things right on it, but you can only spend so much at a time ya know?

 

Will this help you any?

 

Just get him to sign up here

 

it will help me if I have to go down there later tonight to figure it out.

 

He not really much of a computer guy. To busy to play like the rest of us.

He's got the thread to read it though.

 

Ha Ha, touche my friend.

 

Thanks for the help guys.


Seems it was the trailer plug.

The funny thing is, his buddy googled it. He probably found this thread. haha.

He only had a 5 amp fuse left and its working on a 5amp fuse, so I'm thinking he figured it out.