Truck Wont Turn Off

[1-PU70]

Here is what I have fore background info. I took the switched hot wire that was running to my HEI (been that way for years) and used that wire to switch a relay for power to the HEI. Worked fine for about a year. Now here is the problem. When I turn the key off the truck keeps running. This is what I checked. The relay workes fine when the truck is not started. Turn key on relay clicks and switches on. Turn key off and relay clicks and turns off. But when I start the truck and then turn it off there is still some juce at the wire that turns the relay on and off. I used a test light to check the wire that switches the relay and when I turn the truck off from running the the test light glows just a bit. So ther is just enough juce to keep the relay from switching off. What can cause this. I dont think its in the Ignition switch (could be wrong) because it works fine without starting the truck. Could it be feadback from the alternator. Or could it be something else. Need some help. How would you check for alternator feedback anyway.

[70rs/ss]

Change the relay, and then look at the switch as can go bad. Why the relay anyways? I use my HEI to a switched power, no relay just switched 12 volt.

[1-PU70]

Changed relay and no change. I used a relay to get good voltage to the HEI without running through the ignition switch.

[70rs/ss]

Originally Posted by 1-PU70

Changed relay and no change. I used a relay to get good voltage to the HEI without running through the ignition switch.

I ran a wire from the switched terminal on the fuse box, not the switch. When you turn on the key you get power (12 volts) and when you shut the key off you have 0volts, works for me. I have no other guesses other than the switch. You can get one at autozone for like $15-20 and try it, if it does not solve the problem then return it to Autozone and keep looking. There are only so many things that can be wrong. I am thinking the switch is bad and still making contact after you shut it of, have you tryed wiggling the key/switch when you turn it to off position to see if it will shut off. Sorry I cannot offer more help, probably someone else will have more insight?

Mike

[Longhorn Man]

do you have an electric fan by chance?

[1-PU70]

No electric fan(for rad I asume). I read on another site that the regulator could have a bade diod or something so I took off the alternator( Its been converted to an internal regulator) and got one from the Zone ( under warranty no questions asked). Will put it in tomorrrow morning and see what happens.

[Tx Firefighter]

Sounds like an alternator diode is back feeding on your truck.

Andy was eluding to a common thing with electric fans though. Sometimes, you turn them off, and they become a generator, keeping the car running. I've heard of that a few times. It is a wiring issue, not using a fan relay.

[modifiedGMC]

Sounds to me like feed back holding the relay closed. I used to work in a manufacturing plant that built industrial vacuum loader trucks and when we built one with hydraulic cooling fans you could turn the control panel master switch of and it would still be powered for a few seconds till the cooling fan stopped turning. Where are you running your 12 volt battery source from? (this is not a dumb question there are more than one source)

[shifty]

I would test by splicing a line into the original ignition feed and hooking that up - if nothing else, just to isolate the relay as a problem.

[1-PU70]

I have good news and bad news to report. Bad, it wasent the alttenator. Good the truck turns off. Heres wat happened. Before I started having trouble I was redoing the floor. I had just pulled the old mat and insalation and the insalation and cardboard under the dash and on the fire wall. It was realy stuck under the fuse panel. So after the new alternator didnt work I jiggeled the wires going to the back of the fuse panel and the wireing harness through the firewall. Now it turns off fine. So I think I will be checking some wireing before I put new insalation and mat down. Will have to wait till next week for the rest of the story.