Blown fuses

ford
suspension
f150

#1

the fuse for the speedometer keeps blowing. I changed the fuse and the circit breaker in Dec. 6 weeks later the fuse blew again, I replaced it and it last another 2 weeks and blew again. What is causing and what might be the solution?


#2

Something in the circuit is drawing too much power. The circuit needs to be analyzed and any modules on the circuit probed to find the culprit. It could be a bad module or bad wiring. It could even be a bad connector. Electrical issues are notoriously hard to diagnose. Especially today with the large numbers of computer modules and lot and lots of wiring.


#3

Fuses usually supply power to more than one device so the trouble may not have anything to do with the speedometer circuit. A lot of times problems like this are due to chaffed insulation on the wire. You should invest in a factory service manual for the wiring if you are going to work on this yourself. It will pay for itself with this one job. Ebay is a good place to find manuals for a good price.


#4

There are also shops that specialize in automotive electrical systems, in case it isn’t your forte.
My wild guess is that you have a chafed wire causing an intermittent short to ground in the speedo circuit or one related. A specialist shop will have the schematics, wiring diagrams, and expertise to track it down.


#5

Check the wiring harness for the vehicle speed sensor. A frayed wire shorting to ground might be the problem.