ENGINE WON'T SHUT DOWN !! Need Help

[dsmyth]

When you turn the key off everything keeps running except the speedo(if you do it on the move)and the radio. All other guages continue to work. If you stop the engine by pulling the DME relay (dont worry I only do this when parked) the alternater and oil light stay lit. If you disconnect the battery they go out and do not come back on when you reconnect the battery. Then everything is ok until you you try to turn it off again. Its a low mileage 85 .

So far I have replaced the electrical ignition barrel behind the key and disconnected the alternator light to verify the diode is not the culpret.

The problem was noticed on and off for a few days with the engine shutting down 30 seconds or so after the key had been removed on two occasions. Now the problem is consistant, it wont shut down. The key/ignition movement seem normal and steering lock works.

I'm weak on the electrical side and this has me stumped. Any suggestions. thanks Doug

[DRACO A5OG]

What year is your baby?

[slodave]

Originally Posted by DRACO A5OG

What year is your baby?

Read the last sentence in the first paragraph.

[dsmyth]

Its an 85 wb 911

[911quest]

Hey Doug what happens if you unplug the ignition switch connector. Does the car die and all the lights turn off??

[dsmyth]

I guess thats a good place to stary Tony .I will try it in the morning when my body recovers from the ignition switch barrel replacement. I really thought that was going to be the problem. This is starting to look very complicated.

[dsmyth]

I just discovered that when you disconnect the plug from the back of the key the car keeps running normally????

[rick-l]

You have to figure out how the run signal is getting to the DME relay. Is it possible the relay sticks?



edit: that would be terminal 86 on the DME relay.

[dsmyth]

heres the latest ...I worked with an auto electrician today and he told me that if the car turned off with the fan belt disconected to the alternator then the diode is burnt out. The car turned off like it should with the belt disconnected so he replaced the diode behind the guage for the alternator light. I was sure we had found the problem being the burnt diode. It worked properly for ten minuites then would not turn off again when the key was removed.?????
This time when I pulled the DME relay to stop the car only the oil light was left running and the alternator light went out. We retested the diode and it did not fry???. He tested the alternator and said it was running perfectly without any shorts. We again tried running with the fan belt off and this time it would not shut off as it had before?????When I disconnected the battery temporarily the oil light went out and stayed out on reconnection.
Could all this be caused by a DME relay in the first place that also caused the first diode for the alternator to also blow??? This makes no sence to me any longer Help!! Doug

[safe]

First, don't run the engine to long without the fan belt, it gets absolutely no cooling without it.

Second, replacing the DME relay it step no 1 in all DME cars with strange electrical problems. In fact you should have a spare functional relay with you in the car at all times.

[rick-l]

After you verify pin 86 of the DME relay has power with the key in your hand you could try taking fuses out one at a time.