I have a 2003 f150 5.4 4x4. Last night the fuse under the dash that contols the brake lights and turn signals blew I replaced it and it will blow as soon as I use the turn signals or hit the brake pedal. The hazard lights also do not work. This morning I noticed the fuse under the hood number 1 was blown and replaced that and replaced the one inside the truck cab fuse panel again and the one inside the cab still blew. I cannot find any wires that seem to be messed up. I also noticed that fuse 101 under the hood was blown and number 19. I read about a cruise contol problem but I dont think it is for my truck and the cruise contol works fine anyway. I also heard of the multi function switch but from what I have read am not sure if that is my problem. Please help I am stumped was could cause all these fuses to blow?

 

The common connection for the brake light and turn signal would be the multifunction switch. Pull the cover on the steering column and look for any grounding or loose connections.

 

Could it be the multi function switch because the high beams still work and the wipers. They are all connected by the multi switch right? I also noticed that the brake light on the back of the cab does work but the normal brake lights do not work.

 

The multifunction switch does control these functions except the third brake light it runs straight from the brake pedal position switch. This to me without running a meter on the brake pedal position switch would rule it out as the problem. The strange problems I have seen with multifunction switches is the grease that Ford uses dries up and breaks contact. Back in the winter I had a problem with a '98 that the blinkers would not work until the cab warmed up. After taking the cover off and cleaning off the old green grease it worked with no problems.

 

I replaced the multifunction switch today with no luck. Its still has the same problem. I tested the brake switch on the brake pedal and it lights the test light when the brake is depressed so thats not it. I also unplugged the brake pressure switch on the master cylinder to see if that was it. It was dry and did not help either even if I left it unplugged. It has stopped blowing the number 13 fuse when I press the brake but nothing works still. Please help this is driving me crazy and I just paid $152 dollars for a new turn signal switch that did not help anything. I also unplugged the trailer tow harness to make sure that was not it.

 

Found the problem after a $152 multifunction switch that did not work it ended up being the flasher relay under the dash. Thanks for the help anyways.

 

Well drove the truck today and it happened again I thought I had fixed it but I guess I did not. I dont know what else to replace. I did notice now that when I replace the fuse 13 the right turn signal will blink normal but the left blinks slow and gets slower till it pops the fuse. As soon as you hit the brake it blows the fuse also like it was doing before.

 

Do a complete inspection of the wiring harness and grounds going to the lights. Check for contact of metal on the wiring or corrosion on grounds.

 

Here's a thought for trouble shooting, stop down to NAPA and get a breaker to put in place while trouble shooting. It will reset once the power is removed to you can keep hunting without going through a few dozen fuses.

I repaced my fuses on the trailer curcuits with the breakers because I pull other trailers fairly regularly, and don't want to have to replace fuses because some one else isn't as careful with their trailer wiring as I am. If you are going to keep them in place you have to trim the plastic around the fuse socket a little, the angle on the breaker isn't as tapered as the fuses and they won't seat all the way. Drove me nuts the first few weeks with them coming loose after a day or so.

 

Thanks for the input guys. Any place where I can determine which fuse goes with which function? I see numbers on the cover. Does a chart exist?

James

 

Owner's manual.

Steve

 

@ 5.4 4X4

Did you clean the connections on the mf switch and apply new grease when you rpelaced it? And did you check for any damaged wires around the steering column?

 

I forgot about the owners manual. I pulled it out and it had all the info I needed. I had a blown #13 fuse.

This forum helped guide me to the answer......Can you tell I'm not a car mechanic. Major thanks.

James

 

I'm having the same problem has described earlier. I have a 2002 F150 Supercrew. A new fuse will fix the problem but it blows again as soon as I use the brakes. The fuse is for the hazard, brakes and blinkers so all are affected.

Why would the brakes cause a fuse to blow? Any ideas?

Solution Found:

After replacing the 20amp fuse, I tested the blinkers and hazzard lights for a while with no problems. Once I pressed the brakes, the fuse blew.

Realizing that the fuse blew only when the brakes were applied it led me to check the back light wiring and bulbs. For some reason, the bulbs did not match. Bulb Part 3157 are for back tail/break lights. The 2nd buld is the upper white backup light (part #3156). I had Three 3157 lights and one 3156. One of the 3157 lights was a different make and color. I replaced all bulbs (2 3157s for the tail / brake & 2 upper backup lights - #3156).

I hate to say it but I think someone changed by bulb on purpose causing the brake lights to go out. I don't think ford would put mismatch bulbs in their truck.

James

 

Changed MF switch and replaced #13 fuse but blows as soon as I put it in please help!