Continuous run

[MR MOPAR]

I need some help with trying to troubleshoot why car continues to run after main on/off switch is turned to the off position.Chrysler 440,MSD 6AL,MSD distibutor,2 field wires & 1 power wire to 100 amp altenator,MSD is wired large red to on side of switch and also have 24v ignition.Everything for power is wired after the on/off switch and nothing is direct hot to battery terminal. Need help due to having problems with tech lane at tracks.everything else in car shuts down except ignition.:rolleyes:

[BUTCH LaPORTE]

alt is wired to the off side of the switch? if so it is sending power to the igh because the alt is still turning ?

[mrtbolt64]

Stupid question but could the alternator be back feeding the system?

I have seen this happen on a friends boat, alternator had shorted out somehow.

[MR MOPAR]

Car uses factory wiring harness and never had this problem in the past. I have changed nothing electrically in the car for several years and now have blown the dust off the car and this is now my problem so give me some ideas how to correct this please........

[Ed Kurzawa]

You are getting current from the alternator feeding the ignition after main switch is turned off. Is the battery wire terminal on the alternator connected to the original factory harness, or to a seperate wire directly to pos. battery terminal? It should be a seperate wire run direct to battery pos. post when you run a battery shut off switch.When you turn off the battery switch while engine is running the alternator current is backfeeding to the ignition box.That is why you run the wire direct to the battery,so the current has some place to go to when the switch is turned off because as long as the alt.is turning it is still putting out. If you are wired direct to the battery check your grounds.Make sure you have a good ground from the engine to the firewall, as you said the car has factory harness.Scrape off a spot on the firewall to clean bare metal and run a new ground just to be sure. In some cases MSD's do suffer from run on when everything seems right and there is just a tiny trickle of feed you can't get rid of. Go to www.msdignitions.com (http://www.msdignitions.com). Under products section there is a tech page that shows how to eliminate runon with a resistor added to the small red MSD wire for Mopars with problems. I have done it once before for friend of mine, it works. But make sure that main alt.wire goes direct to the pos.battery post or youwill have problems.Hope this helps. Ed SR.

[95silverstallion]

When you say the main + from the alt goes directly to the + battery post do you mean + post on the cut-off switch?

[Ed Kurzawa]

Too the battery terminal post. Not the cut off switch. Hows it goin on the wiring job Brian? Ed sr.

[95silverstallion]

Its coming along slowly. I drive truck so i'm only home weekends. Then I hardly feel like working on the car when i'm home. Only thing I have left to do is the starter wires and the fan.

As far as the above post goes couldn't you run the alt wire to the same cut-off post that the battery + wire is connected to? Would this serve the same purpose as going directly to the + post?

[Ed Kurzawa]

I like the battery post simply because it is direct to the battery itself, not going through another cable and slight voltage drop. If you already got it hooked up do not worry about it. I just try to go direct to the source when I can. The systems that I work on draw far more amps , for hours at a time than you have to worry about.