Truck starting itself (1 Viewer)

[FZJ253]

It's only a matter of time before the old owner of this truck puts two and two together and realizes I'm talking about his truck. I imagine there's not too many 80's out there that have had a winch welded to the frame, a radiator welded into place, or now this...an ignition that likes to fire all on its own, repeatedly, without the key present.

That's the basics: intermittently - every once in a while (once a day, once a week, sometimes once a month) - my truck will turn fire up the accessories, crank, turn over, and run for a few seconds before dying and repeating the process several more times. Multiple times, I've managed to kill the truck by stepping on the brakes, which seems like something..

In general, the wiring situation under the hood of the rig is in questionable shape. There is a second battery present that doesn't seem to be hooked up to anything besides an isolator. There's also a keyless entry system (doesn't work), I suspect an old remote start system, an accessory fan in front of the radiator, and wiring for a light bar that I think I tossed when I replaced its original bumper (i don't remember, but it was probably f****ng welded to the bumper or something).

Where would you start troubleshooting this starting issue? Any suspects - starter, ignition switch, etc? And in general, what would your approach to the errant wiring be - trace back and remove?

 

[ZetheGSD]

I would look under the dash area for aftermarket wiring or any sort and start removing all of it. The random starting has to be related to aftermarket security/remote start systems.

Also if it were my cruiser I would install a new engine harness which is still available if your cruiser is OBD2. This way you start fresh around the engine area to prevent fires or more intermittent wiring issues. Plus I’m sure your EGR harness is nasty.

 

[Rusty Marlin]

Isn't this in a Steven King book. You should burn that Fugger to the ground before it tries to kill you .

In all seriousness, you have a worn insulation problem and a path ground.

 

[BILT4ME]

It's only a matter of time before the old owner of this truck puts two and two together and realizes I'm talking about his truck. I imagine there's not too many 80's out there that have had a winch welded to the frame, a radiator welded into place, or now this...an ignition that likes to fire all on its own, repeatedly, without the key present.

That's the basics: intermittently - every once in a while (once a day, once a week, sometimes once a month) - my truck will turn fire up the accessories, crank, turn over, and run for a few seconds before dying and repeating the process several more times. Multiple times, I've managed to kill the truck by stepping on the brakes, which seems like something..

In general, the wiring situation under the hood of the rig is in questionable shape. There is a second battery present that doesn't seem to be hooked up to anything besides an isolator. There's also a keyless entry system (doesn't work), I suspect an old remote start system, an accessory fan in front of the radiator, and wiring for a light bar that I think I tossed when I replaced its original bumper (i don't remember, but it was probably f****ng welded to the bumper or something).

Where would you start troubleshooting this starting issue? Any suspects - starter, ignition switch, etc? And in general, what would your approach to the errant wiring be - trace back and remove?

First thing i would do is disconnect the battery before it decides to burn to the ground.

There is something in the ignition circuit because it is bypassing the key ignition switch. Yes, I would start under the dash, remove the driver's seat, and remove ALL unnecessary and non-factory wiring.
Second place would be the engine harness above the EGR and split it open to look for melted wiring and/or botched repairs where the wires are shorting to each other and back-feeding to other places.
Third, eliminate the second battery and all associated wiring until this issue is 100% resolved.

 

[Kernal]

Photos of the engine bay, wires under the dash and driver's seat, and other hacks might be helpful (or horrifying).

 

[robnicko]

id have a look at your starter motor solenoid. when my starter jammed on years ago even though the keys were out of the ignition all the dash lights were on as though the key was in the 'on' position. It didnt start though in my case

I put a new starter in and rebuilt the old one and never had the issue since

 

[Tower1]

I read this and hear twighlight zone theme

 

[-Spike-]

It is highly doubtful that a combination of factory wires is shorting in such a way as to turn on the accessory, ignition, and starting circuits in order or at the same time. It's very likely to be a remote starting circuit, which wasn't offered from the factory. Remove the aftermarket remote starter and/or alarm system.

 

[gummycarbs]

I've managed to kill the truck by stepping on the brakes

I suspect an old remote start system

That's exactly what it is, which is why stepping on the brake kills it. That's how it prevents someone from driving off in your remotely-started vehicle: you have you press the brake to shift from park, which kills the engine.

Pull the driver's side kick panel and the panel below the steering column. You'll almost certainly find large (maybe 12 gauge) wires tapped into the ignition wires. There's a large, black, plastic connector right under the steering column that passes the ignition and start wires.