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Fuse keeps blowing when I press the brake pedal on a 98 Windstar. Brake switch is good. Inserted new fuse and the brake lamps do not light up before the fuse blows. Removed all bulbs front and back and the fuse still blows. What to test next?

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    It's a short somewhere on the way to the brake lights. Track the wiring as far as you can. Then go to service.
    – Eugene Sh.
    Aug 25, 2015 at 15:01
  • Find any intermediate connectors between the brake switch and the lights. Disconnect them one by one and see where the short goes away.
    – vini_i
    Aug 25, 2015 at 15:01
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    Try to check if there is a short. If you have a multimeter, set the ohmmeter to the smallest setting. Place one strobe on the "outgoing" pin of the break button and the other to ground (car body). If you read 0, or small numbers - it is shorted. Then follow the two advises above.
    – Naz
    Aug 25, 2015 at 15:02
  • Not on topic here, but get your multimeter, start at the switch at the brake pedal, and follow the wires looking for the short.
    – R Drast
    Aug 25, 2015 at 15:02
  • Somewhere something (a wire or a lamp #3157 socket center pin) is shorted to the chassis. Inspect carefully around the brake lamp sockets and trunk wiring (and anywhere else you think something might have been physically damaged). If it's not obvious by then get the electrical diagrams showing harness connector and splice locations and buzz it out. Or pay someone to do it.
    – Spehro Pefhany
    Aug 25, 2015 at 15:18

3 Answers 3

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Shorts in this system are almost always in the rear of the vehicle. Remove all the brake bulbs, including the center light and inspect the sockets. Carefully inspect anywhere the wires move, like at the trunk lid hinge. Next look for any added trailer wiring connectors, if any disconnect them. After each part is disconnected retest. A short finder tool saves having to blow a bunch of fuses with testing. Year make and model might help...

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  • you can use a brake lamp wired to a dead fuse as a short circuit detector.
    – Jasen
    Jan 24, 2016 at 7:35
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Disconnect battery. Get a continuity tester or a multimeter. Remove bulbs from holder. Test the HOT side of each holder. The ground after all is grounded so the short must be on the hot +12v side. You may find one side or both are shorted. Check your trailer hitch sockets as @Fred Wilson suggests. Also, check your wiring scheme - does the brake switch connect from hot directly to the bulbs or does it go to a relay? The relay could be bad. Some cars - the hot goes to the switch and when the switch is closed it goes to a relay. That then powers the bulbs. So if there's a dead short in the relay, it can be blowing your fuses.

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All the advice / answers above are correct, but I had one car where a broken seat spring was poking a hole into a wire only when the driver sat on the seat - so finding the short may not be easy because it can be intermittant...

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