Electrical Gremlins??
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Senior User
Joined: Oct 2004
Posts: 309
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From: Portland, Maine
Electrical Gremlins??
Ok this ? is for my neighbor whos F-250 SD Gasser is having some serious electrical problems. First in the middle of the night the horn will just start going off then last night he was in the house and the truck was out in the driveway trying to start itself without the keys in the ignition. He went out put the key in and turned it to run and it started and kept trying. I pulled the NEG bettery cable and it stopped. Through process of elimination we have it narrowed down to the underhood fuse box, pass airbag/blowermotor relay circuit......anyone have an idea as to whats goin on or had something similar happen. Almost sounds like theres water in something????
Fleet Mechanic
Joined: Apr 2007
Posts: 1,433
Likes: 7
From: NH
If the truck is equiped with auto start/passive alert etc.. It would be my best guess that it may be the culprit. Was the horn constant or beeping? I couldn't think of anything else that might randomly cause the truck to start other than a malfunctioning auto start system. I am not shure as you didn't specify the year of the truck but it may just be that circuit is tied within the air/bag, blower circuit.
Just a guess on my part.
good luck
Dave
Just a guess on my part.
good luck
Dave
Fleet Mechanic
Joined: Apr 2007
Posts: 1,433
Likes: 7
From: NH
I would seriously consider taking it to a compitent auto shop to be looked at. If your quite comfortable on auto electrical systems and have a service manual i would say tackle this. It's almost quite Obvious he has a short in the starter circuit if the starter continues to run when the key is on. Start your trace from the starter solenoid and work your way back. It is anybody's guess were the short could physicaly be but using your service manual and a quality Digital Volt Meter and some time you may be lucky. Automotive electrical systems have increased 10 fold in complexity over the years. Unless he's a good friend willing to compensate you for your time then i would suggest a shop. They can typically find it quicker in most instances and may be inexpensive. Just remember when making continuity tests have the battery disconnected as to avoid additional shorts that can be caused by yourself as well as there being lethal current levels in the starter circuit.
You could also have a short common in the steering column which is were both the horn and starter/ignition originate.
Good luck
Dave
You could also have a short common in the steering column which is were both the horn and starter/ignition originate.
Good luck
Dave
Post Fiend
Joined: Feb 2007
Posts: 5,078
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From: Rural WV
My vote is to follow Dan's last comments about a short. The horn and the starter are two diffent circuits...but they come together in the steering wheel and at the fuse block....that's where I'd look.
