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!