Hubbsy

My 85 300CD has an interesting wrinkle on the "won't shut off" issue. Engine will NOT shut off when you turn off key until you OPEN driver's door. But if you open the door and manually hold the courtesy light switch IN (off) engine stays running until you release the courtesy light switch and let it pop out to the ON position. Once you release the switch, the engine shuts off immediately. Is there an electrical component to the diesel vac shut off which is controlled by the ignition switch? Can't find info on this.
Any help much appreciated! Many Thx.

Plutoe

There is an issue with your key circuit not supplying voltage to the ECU and thereby turning the car off. However he good news is that you may have created a new option. When you find the failure patent the circuit!

Hubbsy

Thanks. Did not realize 300CD had ECU but apparently 85 does, and guess where it is located? Driver's side lower panel - close to door switch. This could be it. Many thanks again.