Wiring question - Truck Won't Shut Off!

[Guest philedmonds]

I've finally got my B1FA back together, got it running and am checking things out. I redid the wiring on the truck and used modern fuse blocks to protect the circuits. Everything works fine except when I turn the key off, the truck keeps running! After I stopped it, I checked the coil lead and it had voltage with the key on and no voltage with the key off. I have a fuse in the coil wire. Did I screw something up by not completely understanding the positive ground system?

Should I put a ballast resistor in the coil wire or should I have the wire from the coil to the distributor switched? I don't get it! Help! Thanks.

[norrism1]

My guess is you wired the ignition switch wrong. Causing a hot line to go directly to the coil.

[Guest philedmonds]

Maybe I did. I ran a wire from the battery negative terminal (via the starter) to the ignition switch and then to a fuse block. I ran a wire from the fuse block to the coil. I've tested it and with the ignition switch "off" there is no voltage to the coil. With the ignition switch "on" there is voltage.

Doesn't DC voltage flow from + to - and therefore flow all the way through the grounding (the frame in this case) to the devices and then complete the circuit at the negative terminal on the battery thru my wiring? Maybe the coil wire is finding another path to complete the circuit...

[Norm's Coupe]

Don't know what you did wrong without being there. However, you probably have a positive ground truck, just like our cars. So, keep in mind that you are working with positive grounding system, not negative ground. You may have reversed that some place.

Look at the bright side. At least it keeps running. You could have done something like I did when I reinstalled my engine after rebuilding. Had an extra wire that went to the coil. Did not know what that wire was from and couldn't remember if it was hooked up to the positive side of the coil or negative side. So, I just took a wild guess. (not good to assume). Got in the car for a test run (was dark outside) around the neighborhood. Car ran great. Then I turned on my turn signal to make a turn, and the car wanted to die. On one turn I forgot to turn off the turn signal and that's when the car died completely. Since I had forgotten all about the turn signal, I just let the car roll to the side of the street. Then it would not start again, AND, I had no tools or flashlight with me. Looked under the hood for a few minutes and nothing looked wrong that I could see in the dark. Guess it's time to walk home and get some tools and light. As a one last ditch effort, I decided to try to start the car again before walking home. Got in the car and noticed the turn signal switch in the on position, so out of habit turned the signal off. Hit the start button and the car started right up. So...decided it's time to get home ASAP before it happened again. Got to the next corner and turned on the signal again. Again the car started to die. Then noticed it would be ok after turning off the turn signal. Got the car home looked at that extra wire and traced it back to the turn signals. I had hooked it up to the wrong side of the coil. By doing that the turn signal was acting as a cutoff switch. I then pulled that wire altogether, hooked it up to the ignition switch and haven't had a problem since. The PO had hooked it up to the coil before I bought the car and of course I didn't know that until this night.

Moral of that story is. One little wire in the wrong place can cause big problems. On the bright side though, yours keeps running so you won't get stuck like I did.

[grey beard]

Does your truck have an alternator? If it does, this is a very common problem caused by feedback from the alternator, which keeps the coil energized. They each need a separate switch = alternator and coil - or a diode in the line to stop the feedback. JMHO

[Merle Coggins]

I had a similar problem when I set up a temporary control panel to run my truck around without the cab on it. I didn't look closely enough at the wiring diagram and wired it up so that the Voltage regulator was connected through the ign. switch. But when I tried to shut the engine off, the coil stayed powered from the charging circuit so it stayed running. I corrected that, so only the coil was powered with my key, and now it works OK.

So, I would check that you're charging circuit can't feed your ignition coil with the key off. With the engine off, it probably appears OK. But with the engine running, and the gen/alt charging...

Merle

[Guest philedmonds]

Thanks for the information. The truck has the stock voltage regulator and generator. I'll double check the wiring diagram tomorrow. I didn't have this problem when I hooked up temp wiring to run the truck - it is only since i oermanently wired it. i used a simple toggle switch in the coil wire for the temp wiring and it worked just fine. I'm sure I screwed something up! I'll let you know.

[MBF]

When you said you had no power to the coil with the switch off are you sure you were checking the right side of the coil? It's got to be getting some type of feed if it won't shut off. I'd also suspect alternator feedback, but since you're using the original voltage regulator I'd remove the cover and see if the points in the regulator to make sure they're not stuck.

[Guest philedmonds]

I checked power to the coil wire with the truck not running. I haven't checked it with the key off and the truck running. I am pretty sure I am checking the correct coil wire. It is the one that is fed from the fuse box, not the one that goes from the coil to the distributor. I don't have either the truck or "my" wiring disgrams here at the house, but will get on it first thing in the morning at my shop. Thanks for the response.

[Guest philedmonds]

Today I ran the truck and when I shut off the key there was still voltage to the coil. As was suggested, the charging system was feeding the fuse block and on to the coil. I noticed the wiring diagram for the truck had an always "hot" wire from the starter terminal to the voltage regulator, so I ran a wire from the starter terminal to the voltage regulator and out a 30 amp inline fuse in the wire. After that, everything was fine. Thanks everyone for the suggestions and help.