We have a 1992 F150 4x4 (think it's 5.0), automatic Flareside. Pulled the battery from my Explorer and wasn't thinking - hooked up the cables backward. Sparks and smoke everywhere.

So I hooked up the cables correctly and then the parking lights came on, the instrument panel lit up, and the gong came on with the door closed. Connected the starter wire to the solenoid and the truck started on it's own. The starter hung up and kept trying to start (but it's going bad so that may just be it being bad to begin with). The key was not in the ignition, put it in the ignition tried turning it on and off to no avail. Ended up having to pull a relay under the hood to kill the thing as the alternator had already done it's job.

So we looked up some things and found to check the fusible link - it was bad so I replaced it. Problem still occurred.

More research and decided it wouldn't hurt to try a new starter solenoid and I replaced the ignition switch - wires looked ok under the column. Also, replaced the battery.

Still having the same problem. I have tried wiggling wires while the instrument panel and lights are on, but not while it is running. Nothing changes.

Would appreciate some ideas as to what to check next, before throwing more money at the thing. thanks for any help

 

if you can check for a dtc code with a scan tool if nothing occurs i would think you could have killed the ECU/ECM especially if it won't connect, but if one comes up it will narrow down what circuit the problem is in, and i do highly dought it is a mechanical issue, but being a 92 there shouldn't be to much in the way of computerized parts in comparison to new, i'd get it checked by a journeyman at the ford dealership because they'll have an understanding of its computer systems better then any other shop... maybe someone else might have a better idea, i'm just a level 1 ast lol... sorry i couldn't help more.

 

Sounds like you have a section or sections of the harness, the wires that are in it, melted to one another jumping across circuits powering them with nothing turned on.

Extent of damage depends on how long you had the battery connected backwards, the computer it is protected by a diode in the PDB from doing just that so it should be ok.

I wouldn't power it up I wouldn't even connect a battery to it until you find and correct any damage found in the harness.

I'd start at any points you seen smoke rise from, look for any signs of heat damage melted tape distorted harness tubing etc etc.

Might unbolt the power distribution box look at the connections under it.

 

Fried like kfc. Time to get the elctrical kit out. Look for bad grounds and burnt wires like danr said.

 

well I sort of let frustration get the best of me - when I was hooking up the cables after replacing the ignition switch I assumed that when all the lights and instrument cluster came on that it was going to start on it's own also. So I didn't hook up the starter cable to complete the job.

Needing to move the truck I went ahead and connected the final cable yesterday only to find out it didn't start after all. So the ignition switch took care of that problem. However, I am still having issues with the parking lights and dash lights coming on when the battery is connected.

thanks for the ideas, will have to start running down wires now

 

Yup, with some good old investigating you might be able to find the wiring issue. Definitely sounds like it peppered something.

 

You most likely have bits of harness melted together. You're going to have to un-loom a lot of the harness, especially under the dash.

Better carry a fire extinguisher around with you as well.