Brake light fuse

Tiny
NEWLYWED5702
  • MEMBER
  • 1997 FORD F-450
  • 7.6L
  • V8
  • TURBO
  • 2WD
  • 154,000 MILES
Signal lights and flashers work but brakes blow a fuse.
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Friday, March 16th, 2018 AT 6:15 PM

12 Replies

Tiny
HEYMAN1104
  • EXPERT
That is either going to be a wiring issue or an issue with the brake light switch. The switch is located down below the dash, where the top of the brake pedal arm is. Remove the switch and check it for continuity between the lead and ground wires using a Multi-meter or an Ohmmeter. If there is any resistance less than infinity, then you have identified an electrical short. Be sure and check it while pushing the plunger all the way in and out several times.
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Friday, March 16th, 2018 AT 7:18 PM
Tiny
NEWLYWED5702
  • MEMBER
Thanks. There is another issue and I hope they are related. When I turn on the headlights the running lights on top of the cab come on and stay on when I turn off the headlights. Ignition is off and the lights are dim. I pull fuse #4 in power dist box and they go out and stay out when I replace the fuse. I can hear a relay click when I remove the fuse but does not click when fuse is replaced.
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Saturday, March 17th, 2018 AT 7:43 AM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
Remove the stop lamps fuse, place an ammeter into the empty socket, press the brake pedal down and read the ammeter. If it is over what the fuse is rated at, remove all the stop lamp bulbs one at a time checking the ammeter after removing each bulb. If and when after removing a bulb if the ammeter drops safely below what the fuse is rated at, replace that bulb and check that socket and/or wiring for a short if the new bulb does not fix it.
It after no bulbs in, the ammeter still reads high disconnect each item here for fuse #13.
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Saturday, March 17th, 2018 AT 7:51 AM
Tiny
HEYMAN1104
  • EXPERT
Ditto what PRP said. The problem is likely somewhere in the wiring, or possibly in that relay.
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Sunday, March 18th, 2018 AT 3:47 AM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
The other running lights should also stay on because they are on the same circuit. Are they?
I do not see any relays in the wiring diagram for the parking (running) lights.
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Sunday, March 18th, 2018 AT 5:21 AM
Tiny
NEWLYWED5702
  • MEMBER
Yes they are all on and all dim down when I push the headlight switch in. The relay I hear click is in the power dist box.
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Sunday, March 18th, 2018 AT 11:47 AM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
Perhaps you have a short circuit in between the running lights and whatever that relay powers. Try to narrow down which relay it is, either put your finger tips on them and feel which one clicks when someone else turns the headlight switch on and off or remove them one at a time and listen if you are by yourself.
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Sunday, March 18th, 2018 AT 3:02 PM
Tiny
NEWLYWED5702
  • MEMBER
Fuses F & G on power dist box don't have power. Labeled trailer stop R & L
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Monday, March 19th, 2018 AT 4:44 PM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
Was you sure to turn the key to run?
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Monday, March 19th, 2018 AT 5:09 PM
Tiny
NEWLYWED5702
  • MEMBER
Yes. Hazard and dir lights work but no stops. Those two fuses control them but not juice to the fuses
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Monday, March 19th, 2018 AT 5:55 PM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
Those 2 fuses are just for the trailer lights.
I see them listed as fuses 6 and 7 in my book.
Do you have voltage coming out of the stop lamp switch when the pedal is pressed down? If so, check again leaving the multifunction switch.
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Tuesday, March 20th, 2018 AT 7:45 AM
Tiny
NEWLYWED5702
  • MEMBER
I'll ck
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Tuesday, March 20th, 2018 AT 1:36 PM

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