3.2 will not turn-off

[jbrand540]

The problem of the engine not turning off for me began over a year ago. Nothing had been done to the car for about a month when the problem began occuring. At the time I ended up bypassing the factory alarm, replacing the ignition, the alternator, and CHT which made no difference. I had tired of troubleshooting so I had bypassed the main feed to the DME with a sperate relay to turn off with the key and force the system to kill.

Now that winter has come I am trying to properly correct the problem. In my troubleshooting I have removed every fuse except the ful pump as this is necessary for the car to run. I have also removed all relays from fuse panel and those behind the instrument gauges. In this condition the car runs purely off battery with nothing working but the engine and the car will still not turn-off. I am not seeing much else electrically in the way of relay or diode that I would missing but I am sure there has to be something simple that is being overlooked. Someone who had a similar problem fixed it by replacing a power window switch, however, I have bypassed this by removing fuses and power window relays.

This is an pretty much stock 89 3.2 cabrio. Any suggestions that can be provided are greatly welcome as I am at a dead-end as to what to check next.

[rick-l]

You could get out Mr Voltmeter and check that you had the proper input to the Anti Theft Unit from the ignition.

Then check the goes outa of the Anti Theft Unit to the DME relay.

[jbrand540]

the anti-theft Is gone from my initial troubleshooting, however, with ignition off voltage is not present on dme feed. With engine running and ignition off then voltage remains there. I am not seeing what would be left in loop that could hold power on that line.

[chrisp]

subscribing...I have the same problem in my SC. Tried a new alternator but that didn't work. I've heard about a diode somewhere between the alternator and the idiot light that when bad causes this problem. Some of the most experience pcar wrenches I've talked to don't know of a solution or where such a diode would be if not in the alternator itself. FWIW, my racing kill switch shuts the car down fine. So does stalling it in 1st.

[175mph951]

the diode is located behind the gauges....this could case your problem

[175mph951]

also be careful using a battery disconnect switch to shut off car as this can and will blow out the diodes in the alt itself. an alt is not like an old school generator where you can pull the battery cable off to check its function

[jbrand540]

The relay I wired in before rme worked except makes starting hard as fuel pump power is briefly lost when switching back from start to run. If I could solve that I would ignore it.

[jbrand540]

I had tried unplugging apt lite in gauges with no change. Is there something else in that line or would that eliminate that?

[rick-l]

Originally Posted by jbrand540

the anti-theft Is gone from my initial troubleshooting, however, with ignition off voltage is not present on dme feed. With engine running and ignition off then voltage remains there. I am not seeing what would be left in loop that could hold power on that line.

Does this mean with the key in the on or start position there is 12 volts on pin 86 of the DME relay? When you turn the key on and off without the engine running 12 volts at the DME relay logically follows the key position?

When the car is running 12 volts at DME pin 86 does not follow the ignition switch?

[chrisp]

also be careful using a battery disconnect switch to shut off car as this can and will blow out the diodes in the alt itself. an alt is not like an old school generator where you can pull the battery cable off to check its function

I run the 6-pole that's designed to protect from alternator run-on.

Does this mean with the key in the on or start position there is 12 volts on pin 86 of the DME relay? When you turn the key on and off without the engine running 12 volts at the DME relay logically follows the key position?

When the car is running 12 volts at DME pin 86 does not follow the ignition switch?

Is this a Carrera only thing or would this also apply to an SC?

[rick-l]

An SC was CIS and wouldn't have a DME.

What did you do with the alternator light that went through the Anti Theft Unit?

[jbrand540]

For the alt lite I connected the two tegther bypassing the anti theft. Warning lite still works perfectly.

With ignition off 86 at dme is dead. Ignition in run I have 12 volts. If I go back to off without starting engine it goes dead again. Only stays with power when engine is running, however even with all fuses pulled but fuel pump which eliminates charging ability the engine still runs on.

[Trog]

After upgrading my ECU, I had the same problem. After 1984, the factory installed a diode in the BATT light circuit, however if it has failed, your engine will remain running. Try installing a diode here:

[chrisp]

where does one get such a diode?

[rick-l]

You could go to radio shack and buy a 1N4003 and put it in where the Anti Theft Unit used to be in the alternator circuit.

or a 1N4004
or a 1N4005
or a 1N4006
or a 1N4007

[chrisp]

Thanks. I'll try this.

[jbrand540]

That sounds easy enough to try, however, would I not have bypassed that problem by disconnecting the alternator light?

[Laneco]

I see that you did pull fuses - but did you pull the 3 at the rear?

We had a mis-wire back there and ours (converted 80 to 85 3.2) wouldn't shut off. I realize your car is stock and not a oddball like ours, but if one of the wires has loosened or lost insulation it could bridge switched hot with a continuously hot circuit.

Easy to check and eliminates 3 more fuses...

angela

[jbrand540]

I do have those 3 out as well along with blower relay.

[rick-l]

The Blue-red wire from the alternator / Anti Theft Unit also goes through a diode to an electronic module called "Switching for Catalyzer M193". Anyone know what that is?