Got a good one here baord, figured this is the best place to find the solution to a problem i haven't been able to track down. I had a turn signal bulb go out this past weekend and when i got the replacement in i noticed that when my left (drivers side) turn signal is on or when by foot is on the brake, the fuel pump to my front take is running. With the turn signal, it runs intermittant with the flash, with the brake, the pump runs as long as my foot is on the pedal. Also, along with all this, i found that with the truck running my tailights do not shut off until i turn the key off. They're not on all the time, only when i'm useing the headlights, then when i shut off the headlights the tailights stay on, till i shut off the truck. I've looked through my Haynes Manual and traced what i could see of the lines, don't see anything shorting out against anything. What else could this be??? Thanks Soooo Much for the help.

Mike
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Check your ground straps , Yes you got a short somewere

 

It seems to me that you have a short between your fuel pump and your parking lights and turn signals. You might wanna check anywhere any wires for both the fuel pump and lights are near each other, specifically behind the fuse panel. Also check the wiring harnesses as well.

Hope this helps.

 

Seems to me that the rear tail light wires & the fuel pump wires are all in the same wire loom . That may be an area to inspect .

 

Thanks for the tips board. I'll let you know what i find. Course, if i can find it. :-)

Mike
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Get a preist and perfrom an excorcism right away!!!!


-Chris

Big Red Ticking 92 F150

Tick,Tick,Tick,Tick,Tick,Tick,Tick,Tick

 

Ok, so i just got done walking along the frame rail of my truck, looking for anything that could be causing this short and found nothing. I did however figure out tonight that when i'm running on the back tank, i have no problems, everything works as it should, lights, blinkers, fuel pump etc... when i switch to my front tank i have no left turn signal (it lights but don't blink), rear parking lights don't shut off, front fuel pump runs when i'm on the brake, uhh? oh yeah, the turn signal works with the key on, till i start the truck then nothing. Course it's running the fuel pump on each flash as it was before....ANY idea's?? I think i've narrowed it down a bit but the problems still got me dazed, & confused.

Mike
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I would have to say that it is in the wiring somewhere that the 2 circuits follow the same path. I don't know if you actually tore the harness apart to find it, but they are usually taped up and hard to find anything unless it is untaped. Just be sure to retape it back up and put it back where it came from in a way that it won't rub any sharp edges. I've also heard something about taking a compass and following the wiring with it, and when it gets to the break in the wire, it will change directions. Never tried it yet, but I think it would work.
I also just read in another thread about the same type of thing(electrical system goes nuts) and somebody wrote about their friend found the bulkhead connector at the firewall had wires where the insulation shrunk back and allowed a few things to short across.

88 F-150 4X4 XLT Lariat w/5.0 EFI 5 spd (DAILY DRIVER)
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Trace the wires from the fuel tank selector switch & from the wiring coming from the turn signals , the short may be in that area . A wiring diagram would help you a lot if you dont already have one .

 

You have a bad ground probably on the turn signal circuit. Dc voltage will find a way to get to ground if it has to pass through several devices to get there.

 

From my Haynes manual, i'm haveing a hard time makeing heads or tails outta these electrical system diagrams, anyone out there can tell me which ground the directionals are on. From what i can make out, it's the "E" ground and mine is fine. I'm still locating some of the other grounds to check.

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