1980 242 (B21F)
Problem is motor will not turn off with ignition key switch.

Motor will however turn off properly when single small red “amp” wire is disconnected at alternator.

Red “AMP” light in dash will not light up with motor off and key in “on” position. It will however light up properly when small red “amp” wire is disconnected at alternator.

It appears that voltage is feeding back through to coil bypassing ignition switch.

I have another properly working 85 244 that I have used to make some comparative voltage readings. I took voltage reading with ignition on, off, running, connected & disconnected. Here is the only real different or suspect voltage reading between the two cars:
Red amp wire (connected at alternator spade lug terminal) with motor off and key in the “on” or “run” position.
1980 242 (problem car) 5.9 volts
1985 244 (good car) 2.3 volts

Update: Now it seems the car has decided to temporarily start working properly and here are the differences I can see:
Red “AMP” light in dash will now light up properly with motor off and key in the “on” position.
Change in voltage reading at red amp wire/alternator terminal. With motor off and key in the “on” or “run” position voltage is now 1.7 volts. (this was 5.9 when not working properly) .

This is my Daughters car and she’s a teacher so needless to say she can’t afford professional repair or a new one at this time. I’m bound and determined to get this thing fixed for her! With your help I feel we can do it!

Anyone have any experience with this type of problem or even a good guess?

Thanks for your help!

Dale,
When you said in your original post "I forgot to disconnect the battery and wire did arc during reattachment to spade lug." was the motor running at that time, or was the ignition switch on (position II) but not running? Between what and what else did the arc occur. I don't have much luck when I assume things, like it arced from the red wire terminal end to the correct spade lug on the alternator.

I would not expect you would have needed to disconnect the battery to re-attach the small red lead safely.
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Art Benstein near Baltimore

check the harness for the relay, could be the blue/yellow and red wires have melted together and that could feed the ignition. good luck, chuck.

does this car have ac? if so, there is a relay that is in the charging system. it's job is to delay starting the ac compressor until the alternator charges. it's on the passenger side of the console, maybe between there and the glovebox. has 5 wires on it , red, blue/yellow, green, white and brown.
pull the relay out and try again. the red and blue/yellow circuit are the 2 we are concerened with. if that's it, thank art benstein. he remembered it. they only put that relay in the wiring diagram under air conditioning, never under charging system. you still need to check the alternator and make sure the red wire you fixed does not have voltage on it with the key off and the wire plugged in. this means a bad diode in the alternator. keep us posted, chuck.

You don't mention if you have replaced the ignition switch. The switch sounds messed up to me.

Lots of clues are in here . Some excellent methodical troubleshooting by porkface, unfortunately electrical trouble tracing is step-by-step work, not always easily bypassed by guesswork and symptom-part mapping.
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Art Benstein near Baltimore

There was a post awhile back, where the engine would not shut off. Even with the key removed. The driver had to remove the +ve(?) lead at the battery to kill the engine.

I forget what the solution was but it may have involved the starter wiring.
Maybe somebody remembers that thread.
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1980 245 Canadian B21A with SU carb and M46 trans

Just a guess ,but have you check the engine wireing harness? The tend to get brittle and the insulation falls off ,causing all kinds of problems. Check up by the "grey box" it's a grey wire junction conector located just off center on the firewall(top) in the engine bay. if it crumbling there most likly its crumbling in the harness too. replacement is straight forward and easy if need be.
Good luck.
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Dan D. '85 245 DL , '93 945 .Delanisdjd@aol.com