Wiring headache

I am just finishing my car and its finally ready for the street. I took it out for the first test drive and my transmission went...So I pulled it and replaced it.

Now this is where the headache starts. Before the first test drive everything seemed to work perfect. Started up right on, electric fan works off a temp switch and that worked just fine. Now since the reinstall I am having a problem with run on. Car starts but won't key off and I have to pull the coil wire. I have checked all my wiring. Only wiring I really had to undo was the distributor and sender wires for my gauges. I have since changed the key switch, and starter solenoid and still the same. I just don't get why it worked before and now it doesn't. I did have a short that I found where I was blowing some fuses but since I found it, it is no longer an issue. Any ideas where I should start? Obviously something on the ignition since is recycling through....Alternator? Voltage regulator? I am running a Mallory Unilite with seperate coil if that helps any....


Thanks for the help in advance

 

need a diode in your power to alternator wire.

 

It is a one wire alternator...I haven't heard of those needing one too often but I'll have to try that too

 

as yblock292 said a diode or bulb in the exciter line going to the alternator.

 

sorry i type slow. a one wire alt. does not have a exciter wire. does it have power to the coil with it not running? if it doesn't then it is feeding back through the charging system. if it has power when it's not running then you have to trace back from the coil till you find the power connection.

 

put the wire to power your ignition on the ignition terminal of the ignition switch. that should be the only wire on that terminal. if you need switched power connect them to the accessory side of the switch

 

33, You might need that diod in the power wire to the fan, If the fan was running when you turned off the ign. switch and the car ran on that may do it. good luck! Normal Norman

 

Does the one wire from alternator go directly to the battery or is it possible that it is connected to ignition terminal of ignition switch? What car, engine, etc. are we talking about?

 

Fan should be wired thru relay, It's pretty hard to get back feed from 1 wire alt, if it goes to battery or bat. post on solenoid.

 

Well I dont think its back feeding from the alt. I unhooked the alt to see if it would still do it and it did. I ran the car long enough to get the fan to come on and it did. The fan is being run with a spal temp switch and harness that runs from a relay. The wiring harness is a T bucket harness from painless so I've been talking to them too. I guess I'll have to start pulling fuses...Do I pull the fuses while car is running and see which one it takes to kill it?

 

Get a diode from radio shack. I have the part number give me a second.

 

276-1661 is the Part #.

I had the same problem.

 

Is the fan load and relay load both getting its power from the ign?The fan may be feeding the relay resulting in a backfeed.The temp switch and relay coil should come off the ign and the fan load should come from an all time hot or a acc power.

 

Yes keep the car running to check thur fuses. Where is fan relay power coming from.

 

So I pulled it and replaced it.

Did you put another trans in it? Same type? I know you are going to find this hard to believe but a friend of mine that owns a salvage yard sold a auto trans to a guy and after he installed in in his truck he came back and told him that when the truck would shift gears, it would change the station on his radio. My friend went for a ride and it would do just that. The trans was a year newer than the truck came out with and it turns out there was a wire to the valve body or something in the trans that had a ground wire the original tranny did not have. It was feeding back through the harness and caused the radio problem. Removing the ground fixed the problem and the trans still worked in the truck. I am just saying this because when a problem like this happens, you always want to go back to whatever was just changed and have a real close look. Dennis D

 

It's the fan relay! Try pulling the fuse that operates the fan relay and I bet it will stop the engine with the key off. Had the same issue running a relay to my fuel pump and when I shut the key off it would continue to run. I wired in a toggle sw. for the fuel pump power and if I shut the fuel pump off first, then the key will stop the engine.
Funny thing was mine didn't do this when I first got the car completed; it cropped up shortly afterwards, and I changed ignition sw. thinking it was shorted.

 

Well I got it to shut off by pulling fuses and I have narrowed down to the radio/constant hot circuit on my wiring harness. Dennis D, the trans was just a th350 nothing too special or electronic for that matter. But I was going to look at that ground since I have it grounded at the transmission.

 

Got 'er all figured out and fixed....thanks for everyone that had input I appreciate the help.

 

Well, what did you find? After thirty five years working on electric forklifts I have seen some wierd things a bad negative will cause. The trans I was refering to was one of the new fangled ones with OD and lockup and such. Dennis D

 

Well lesson learned its better to do everything yourself. I had a buddy of mine help wire my key switch and he misread a wire that said accessory constant for accessory B+, and kept feeding power back through.....

 

good deal, need to back check other peoples work or DIY.