Trent Hamilton

2006 ford f150 lariat 5.4.

The brake lights were on. Found fuse 14 was blown. Replaced the fuse. Turned the key fuse blew again.

So i started unplugging sensors and replacing the fuse. Finally came to the passenger side speed sensor. Unpluged that replaced the fuse. Turned the key. Fuse didnt blow.

Replaces the speed sensor today. Drove it about 2 miles brake lights came back on again.

Got it home. Checked fuse. It was blown again. Replaced fuse. Turned key. It blew again. Unplugged speed sensor in which i replaced. Replaced fuse. Fuse blew again.

My question is. Since i replaced 1 speed sensor. Could another one go bad that quickly?

650NutKase

According to the repair manual that I have, that fuse controls these items:
Back-up lamp and Daytime Running
Lamps (DRL) relay coil, A/C pressure
switch, Redundant speed control
switch, Heated PCV (5.4L), Trailer
tow back-up lamps relay coil, ABS,
Reverse park aid, EC mirror

Check everything here (if equipped) to make sure nothing is messed up. A circuit breaker fuse is going to be your friend here. Instead of buying so many 10a's lol

PerryB

On the list above, my two primary suspects would be the reverse lights and the heated PCV. The EC mirror gets a blip on my radar also, for personal reasons. We have a 95/250 at the ranch that kept blowing the back-up light fuse. In this case the EC mirror is NOT listed in the fuse legend but does in fact draw from that circuit. It took me a long time to find it, I ended up borrowing a "pinger" from a friend and chased the electromagnetic flux to find the short. The wire in the headliner was chafed through to a screw.

who_knos

Hello, I went through this my self. I started at the heated PCV and seen the wires was burnt together, then I unhooked it and it was still blowing the fuse. Next step I removed the engine harness from the truck and split it open looking for a bad wire no dice, but it stayed for a day then popped....next unhooked and removed ecm cleaned the grounds and shook and tapped it to see if I could hear anything like a chunk of solder maybe causing it...no dice. I dont suggest it but I was up to a 35-40 amp fuse and it just blew like the 10. I then unhooked ecm replaced the fuse turned key on and hooked up one connector at a time till it blew and I found out it was the center one making it blow. To shorten up my frustration I ended up unhooking the center connector and taking the natural wrap out of the wires....meaning twisting it backwards to get the wires away from each other and it lasted a year...I traded the truck off and it was still good. In short...unhook/inspect PCV wiring and retwist the center ECM connector and see if it helps.

techrep

iTrader: (1)

I would toss in ..checking out the 7 pin connector for trailer towing.. it gets corroded and can cause shorts.

who_knos

Good point but is there a keyed power on wire back there? If Im reading right its doing like mine did, it would blow as soon as the key gets turned on. I do feel his pain if I hadnt found the ecm connector I did buy some heavy duty wire and a heavy duty push button switch to put in place of fuse..not the most correct way but would of been effective....lol..push and look for smoke the OPs problem can be frustrating so I feel for him.

Jamieat

You could take out the reverse and brake light bulbs, turn the key, see if the fuse still blows.

Then, insert bulbs one at a time and check. This may at least help you isolate the issue if plugging up a particular bulb causes the circuit to pop.

One of your bulb harness could be bad, bad connection, or debris in the base causing a short across terminals.

I always start with the easy, rule it out, move on to next..

Make sure none of the metal tabs on the harnesses are broken inside and is causing it to short. I had this happen to me, brake bulb harness corroded and when I changed bulbs, the tab fell to the bottom and shorted out.