I'm not sure why it continues to blow. When I put a new 20 amp in and hit the brakes, it blows. What is really confusing, it did this one day and all of a sudden for about 6 months, no blowing of the fuse. The other day it returned.

Any advice would be greatly appreciated.

 

If it blows only when the pedal is pressed, you have a short circuit in the brake lamp circuit.

It might be a bad lamp socket or a wire that is chafed or crimped, but you won't know until you find the actual fault.

Unfortunately, finding a short circuit is often a tough job for someone who isn't trained in how to do so. The best someone in that situation can do for themselves is to do a thorough visual exam.

 

Ive taken the bulbs out, and completely disconnected the tail lights, still same thing.

 

Are you 100% positive it blows ONLY when the brake pedal is pressed? This is a critical observation.

Did you also check the third brake lamp? Dis you have the cruise recall performed?

Bottom line, if you don't already know how to diagnose a short circuit in a wiring scheme, you're not going to learn how in a few internet posts. Check the accessible stuff first, but, if you don't have the testing tools and testing knowledge, take it to someone who does.

 

I'm pretty sure. I'm going to have to get some more 20 amp fuses to test. I'm not totally positive I'd I had the cruise recall done. I had a couple different recalls which some turned out to not be my model.

I did have my cruise control quit on me about 6 months back which around the same time the 13 fuse was blowing. I went to the dealership and got a 12 dollar part and fixed the cruise. It was a simple harness. The old harness had a fuse inline which said it wasn't serviceable.

 

If you replaced the harness to the switch on the master cylinder because the inline fuse blew, you have a leaky/defective switch. For the moment, simply unhook the switch (you will loose cruise control) and see if the problem with F13 goes away since F13 is always feeding power to that switch.

 

No go.

I unpugged the new harness and put a new fuse in, and it blew after a while of using the blinkers and brake pedal. Did this three times, three fuses blowing. Plugged the harness back in, blew again.

#13 fuse is for the stop lamps swith and turn/hazard flasher correct?

this is the harness

 

Did you ever check the HMSL?

 

i did.


hmsl??

 

HMSL High Mount Stop Lamp, I would guess a fast key'ing on the C in CHMSL.

Since you unplugged the recall harness from the truck and had the same issue, next I would unplug the BPP ( Brake Pedal Position ) Switch on the brake pedal, and try jumpering the brake lamps, to see if it blows.

The wires you want to jumper to activate the stop lamps are the Light Green w/ White stripe to the Light Green wire on the connector.

If you can jumper them, and the fuse holds, I would guess at an issue with the stop lamp switch on the brake pedal.
- You would need to test the Light green wire side to ground for continuity when you press on the brake pedal. If your meter does not have a continuity setting, just use the resistance / ohm setting, and look for a reading that is anything but infinity ( might should as a . or blank display same as the leads not hooked to anything ).

I can only recall 1 that the switch was the cause of the fuse blowing, guess it was shorting to the brake pedal on the Light Green side, and when it was activated it was a short to ground.

 

I do have a tester with continuity. How would I go about testing the high stop lamp? take the bulb out?

Where are these wires I need to jumper?

thanks

 

How did you check the CHMSL before, when you said you checked it ?

the wires to jumper :
BPP ( Brake Pedal Position ) Switch on the brake pedal

 

Never said I checked it. He asked me if I checked it and asked about the cruise recall.

I stated I wasn't sure about the cruise recall.

The switch on the brake pedal under the dash correct?

 

Think I narrowed it down to the steering column. After trying to track the reason for the fuses blowing for a couple weeks, all of a sudden the fuses quit blowing and nothing did not work.

I found a person with a similar problem and stated that he tilted the steering wheel up. For some reason the wiring in the steering column going to the multiswitch is sorta short and comes loose. I attempted this and instantly got my blinkers back. No hazards. I also have noticed that the left blinker works fine clicking. When I turn the right blinker on, the clicking becomes somewhat labored, like it is having a tough time working. Im thinking something on the right side or something controlling the right side is shorting.

any advice

 

Here is a list of things I have done to eliminate sections.

I unplugged the big harness in the rear of the truck running inside the frame that feeds the taillights, trailer harness, liscense plate etc..

I unplugged the brake pedal switch and the fuse popped with the right blinker.

I replaced the brake pedal switch and it still popped with the right blinker or brakes.

I replaced the multifunction switch with a new one, no go

Changed the flasher relay to a brand new one, no go still

I replaced the multifunction switch harness with a new one because the old one wires pulled out a little.

I checked continuity on the multifunction switch harness and the big harness under the dash that feeds it, all wires matched up with none touching other ones.

I unplugged the harness on the cruise control directly from the master cylinder and everything started working. It worked for a while. I drove down the road and hit the brakes, hazards, turn signals, everthing worked, then POP. when i hit the brakes, it popped.

For some reason Im getting a fuse pop every time i hit the brakes again. hazards too.

I was thinking the cruise has something to do with it, because I have got everything to work three times today by unplugging from there.