Fuse #13 keeps blowing
Thread Starter
|
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
Fuse #13 keeps blowing
(cross-posted from the Excursion forum)
Every time I step on the brakes, there is a bright spark in fuse #13. My brake lights, turn signals and hazards don't work. At this point my truck isn't drivable.
According to the owner's manual in my truck, says circuit #13 is for "stop lamps, CHMSL/hazard, trailer tow stop lamp, and speed control."
I'm assuming that the hazard part covers the turn signals as well, but I know the cruise control works even when the fuse is blown. I used it last night on the way home (this was before I realized I didn't have brake lights).
So I know I have a short somewhere. The only mods I've done to the lights are aftermarket headlights, but if the fuse only gets blown when I step on the brakes, I don't see what that would have to do with it. Also, the lights have been installed and working for about a month before this started. The only thing that I did around the same time was install the gauges. I ran the power to them from #5, the customer access circuit.
Are there any other "common" areas for this to happen? I already removed the rear brake lights and it didn't help. I am quickly running out of 20A mini fuses.
Every time I step on the brakes, there is a bright spark in fuse #13. My brake lights, turn signals and hazards don't work. At this point my truck isn't drivable.
According to the owner's manual in my truck, says circuit #13 is for "stop lamps, CHMSL/hazard, trailer tow stop lamp, and speed control."
I'm assuming that the hazard part covers the turn signals as well, but I know the cruise control works even when the fuse is blown. I used it last night on the way home (this was before I realized I didn't have brake lights).
So I know I have a short somewhere. The only mods I've done to the lights are aftermarket headlights, but if the fuse only gets blown when I step on the brakes, I don't see what that would have to do with it. Also, the lights have been installed and working for about a month before this started. The only thing that I did around the same time was install the gauges. I ran the power to them from #5, the customer access circuit.
Are there any other "common" areas for this to happen? I already removed the rear brake lights and it didn't help. I am quickly running out of 20A mini fuses.
Fleet Mechanic
Joined: Nov 2011
Posts: 1,825
Likes: 43
From: Land of Taxes
Could be any of the components in this circuit? My first bet is on the brake light switch, the brake bulbs or their sockets. The brake light switch could have a broken contact floating around in it? Second bet is the aux trailer light/brake circuits.
The easiest way to locate the short is to eliminate each component one by one until the fuse stays closed.
An ohm meter and your eyeballs are your friend here.
The easiest way to locate the short is to eliminate each component one by one until the fuse stays closed.
An ohm meter and your eyeballs are your friend here.
Thread Starter
|
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
I already removed the rear tail lenses completely.
Where is this brake switch? I plan on looking at the rear wiring harness when I take a look at it later today, but it seems more likely to me it's under the dash because that's where I was working when this started.
Where is this brake switch? I plan on looking at the rear wiring harness when I take a look at it later today, but it seems more likely to me it's under the dash because that's where I was working when this started.
Elder User
Joined: Nov 2004
Posts: 614
Likes: 1
From: Fort Wayne IN
The brake light switch is attached to the pedal. Take a close look at the plug and wires that go to the switch.
Thread Starter
|
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
The wires going to the switch are red/lt grn, lt grn/red, red, lt grn, and dk blue/black.
I know the red comes from the PCM power relay, lt grn/red is the power from fuse #13, but I don't know what the other wires are for. My haynes manual says that blk/yel is to the cruise servo, but I'm thinking that's the dk blue/black wire.
Question: If I check the continuity of the lt grn wire, which is the wire that runs back to all 3 stop lights, and get close to zero, it means the short is between the brake switch and the lights themselves, right? So under the chassis somewhere?
Does anyone have a GOOD wiring diagram?
FTE Chapter Leader
Joined: Feb 2004
Posts: 14,904
Likes: 76
From: Wayland, MI
Trending Topics
FTE Chapter Leader
Joined: Feb 2004
Posts: 14,904
Likes: 76
From: Wayland, MI
I would definitely check the trailer connector, flip it open and make sure that all the pins are not touching, and also check the wiring connector that runs to the plug. I have seen them corrode enough to short. I have also seen them bent and wire pinched from backing into snow banks.
Just a couple ideas. Chasing down shorts are never fun. Best thing to do is start at one end and work to the other. That way you have an idea of what you have checked along the way.
Just a couple ideas. Chasing down shorts are never fun. Best thing to do is start at one end and work to the other. That way you have an idea of what you have checked along the way.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Postmaster
Joined: Jun 2014
Posts: 3,206
Likes: 3
From: Oakhust NJ Jersey Shore
I take it the turn signals, and 4 ways are working fine? it's only when you hit the brakes? the green wire is what feeds the brake light circuit. Do you have a electric brake control on the truck? Ford gives you a gray connector under the dash to plug in an aftermarket brake control, make sure nothing is hitting or plugged into that connector. the brake light wire goes to the combo switch, (turn signal switch), UNPLUG THAT FIRST AND HIT THE BRAKE AND SEE IF IT BLOWS. If it does than you know it's between the brake light switch and turn signal switch, if it doesn't replace your electronic flasher, it's backfeeding the combo switch. the wires that do the turn signals are the same as the brakes, so it's nothing under the truck or carpet, It's in the 3rd brake light, combo switch, or last flasher.
Thread
Thread Starter
Forum
Replies
Last Post
351Cleveland C4
1967 - 1972 F-100 & Larger F-Series Trucks
12
Jan 20, 2014 07:49 PM