Questions and Answers

Plymouth Valiant Will Not Shut Off Q. Hiya, am writing in regards to a dilemma I am having with a vehicle repair. I have a 1968 Plymouth Valiant with the Slant Six 225 CID engine and 150,000 miles. My wife brought it home one night after school and it would not shut off. I wasn't thinking when I went out to look at it and pulled the coil wire out to shut it down. I should have just starved the engine of air instead.

Well anyway the coil wire broke about an inch from the end and was shooting sparks throughout the engine compartment. Since then I have replaced the Ignition Switch, The Ballast Resister, The Voltage Regulator, and the Starter Relay.

The car still starts but does not want to shut off, and also when the key is in the OFF position with the new switch the oil light is on. Once I move the key to the RUN or ACCY position the oil light goes out.

I can not figure out why the car will not turn off when the key is put into the off position, or why the oil light is now on in the OFF position. The Valiant is a very simple car yet I am at a loss. There are only a few items under the hood and they have all been replaced.

Thank you for your help.
Dave

A. You have a short in the harness somewhere then. The ignition switch sends power from the switch through the brown wire to the ballast resistor, then from the ballast resistor to the + side of the ignition coil. At the same time the ignition switch send power through the gray wire to the Oil Pressure Sending unit. When the key is in the OFF position, the ignition switch cuts power to these two circuits.

Assuming the ignition switch you put in is good, then somewhere power is getting to the gray or brown wire. Now, funny thing is with this system, a bad alternator, internally shorted, can feed power back through the voltage regulator, to the ballast resistor and to the ignition coil. These are the only two possibilities, besides the ignition switch, that will cause the problem you are having.

Here is a wiring diagram in case you need it.