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Author Topic:   F-150 Brake/ Wiring problem
bullittwrench
Dirt Roller

Total posts: 8
posted November 23, 2005 07:19 PM  
Please bear with me, this is kind of long winded. 1991 Ford XLT Lariat 4x4, 4.9L, auto-o.d., f.i., rear abs brakes, 81500 miles.
I just bought this truck. Right before I got it the master cylinder was changed. Now the abs and emer. brake lights stay on all the time and it blows the brake light fuse. With a new fuse and the truck in park idling, the brake lights work fine. I can jab the brakes and also hold constant pressure on them and they work fine. As soon as I move the truck front or back and apply the brakes, the fuse blows.
I have unplugged the rear wiring harness at the back bumper, the sensor on the rear diff., and the prop. valve on the frame rail under the cab and it still blows the fuse. I followed the wiring from front to back and couldn't find anything pinched, rubbed or bare.
Can anyone help me find this problem?


Thanks
bullittwrench
wsmith@acsworld.com

Spi-nex
Dirt Full Roller

Total posts: 62
posted November 23, 2005 08:31 PM  
I had the EXACT same problem with my F-150 XLT Lariet.

What I finially had to have done was have my turn signal switch system (in the steering column) replaced. The turn signal wires have to trip a relay when your applying brake to shut off 1 of the lights in the back of the truck off (which ever light is blinking when your gunna turn) so if something gets messed up in the wiring in the turn signal switch system its gunna overload, blow fuses out, etc.

Once I had the switch and wiring replaced in my steering cloumn, BOOM it worked A-Ok!

Temporary Fix (Warning: Redneck Way!) For a temporary fix of the sitiation, take a 8-10 gauge wile cut it about 3'' long, srip a 1/2'' off each end, take out the blown brake fuse, take the wire, put one stripped end into one side of where the fuse go, and take the other side of the wire, and jam it into the other side of where the fuse goes. I ran my truck for over a year like that, no problems.

But get ur turn signal system replaced in the steering column, thats what fixed mine.

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Jonathon R. Huston
#81 Factory Stock

bullittwrench
Dirt Roller

Total posts: 8
posted November 25, 2005 04:11 PM  
Now we have a new twist, today after work I started her up and the turn signal flasher in the fuse panel was pulsing like the turn signal was on, but they were not. The signal arrows on the dash were not blinking either.
Is this just an extension of the same problem? Should I replace the turn signal mechanism or is it a short in the steering column? HELP

bullittwrench

Spi-nex
Dirt Full Roller

Total posts: 62
posted November 25, 2005 04:28 PM  
There are 2 Flasher mechanisims In your truck. 1 In the fuse panel, and 1 around the glovebox area. 1 of the 2 controls the Hazard lights, and the other the turn signals. Try turning your Hazards on, if they are on, then the mechanisim around your glovebox is fine and the one in your fuse box needs replaced.

Likely the whole thing in your steering column is shot like mine was and once it was replaced all my problems stopped.

Try also slightly moving the turn signal lever without actually tripping the turn signal. Your lever may not be completely deactivating the switch when it is in the middle position.

If there is a short in your column is shows it is spreading from blowing brake fuses to turn signal flashers. GET IT FIXED before the problem spreads to the computer brain.

------------------
Jonathon R. Huston
#81 Factory Stock

[This message has been edited by Spi-nex (edited November 25, 2005).]

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