The Stovebolt Site Forums The Shop Area The Electrical Bay Truck Still Won't Stop Running

Several weeks ago I posted this problem with my 49. Chevy Duty wiring harness, 12 volt with alternator. The only way to shut the engine off was to disconnect the battery.

With everyone's help, the ignition switch was the suspect so I took it apart, cleaned, etc. and it bench tested ok.

I started it up tonight and same thing, except now even disconnecting the battery doesn't shut it off (I guess it would eventually) I shut it down by pulling the coil wire.

I'm going to swear (until proven wrong) that all of the wiring is correct.

I read an archived post where someone had the same problem with a 59 and solved it by installing a 12 volt warning light (resistance???) in the line running from the ignition switch to the alternator.

I'm open to suggestions, I'm in over my head on this one.

Thanks,

You need to check the wire going to the + side of the coil, if this wire has voltage with the key off you need to find where the voltage is coming from,the coil should not have power with the key off. If you disconnect the battery with the engine running the engine will continue to run as long as the alternator is charging, but doing this can damage the alternator.

Thanks. I have two wires going to the (+) on the coil.

1.Line from ignition switch with the ballast resistor. This one seems to be ok.

2.Line from side terminal of starter switch. This one is hot with or without the ignition on. I guess that makes the starter switch the newest suspect. And it is a new switch. I'll have to take it off and have a look.

Am I correct that the side terminal should only be hot when the switch is depressed?

If you are using a GM alt. with internal regulator
you must have resistance or a diode in the signal
wire from the ignition switch. I use a dash light
with plastic socket & 2 wires. That also gives
you a warning light.

About your two wires going to the + side of the coil:
1. wire from ballast resistor is correct.
2. this wire should go to the ballast resistor bypass terminal on the starter motor. If there is no bypass on your starter motor, you can wire it to the starter switch. However it should only be hot when the starter switch is activated. You said it is hot all the time? That's not good for your battery or points.

Try this: disconnect the second wire on the coil so the only wire to the + on the coil is the one from the ballast resistor. Start the engine. If you can shut it off normally, you have ruled out the alternator as the problem.

Does your alternator have a DA plug (two wires) on it? If so, try disconnecting the plug and shutting off the engine. That will rule out the alternator if it shuts off with the DA plug disconnected. The sense lead of the voltage regulator is supposed to be connected to the battery but the indicator is supposed to connect to a switched source. If they are backwards the alternator will power the ignition through the regulator and it won't shut off, although if there is a bulb or diode it should prevent that.
Also, some ignition switches (the one on my '50) have two accessory terminals that are isolated, so you can connect the accessories and alternator to one and the ignition to the other and prevent that problem.

I didn't have this problem ... but my engine was "running on" just a tad when I shut it off, until I installed a diode on the wire that goes to the alternator from the ignition:
[img]http://www.alanhorvath.com/54chevy/chevypics/wiring_1.jpg[/img]

The starter switch appears to be the guilty party. I disconnected the wire going from the side terminal to the coil and everything works ok. The starter switch is new. I haven't had a chance to pull it out and see what the problem is.

Thanks everyone.