It won't start!

I'll start from the beginning. Car is a '98 M3 Sedan.

In the fall it quit turning over but all of the lights would light up. I would pop the clutch and it would start right up. When I would turn the key back off it wouldn't shut the car off. I would have to kill it with the clutch.

I suspected a bad ignition switch so I bought a new one. I took it apart and tried both the new and old ignition switches and they both would not turn over the starter. Since I thought that it wasn't bad I put the old one back in. I put it all back together and it turned over just fine again.

It worked for a few months and then all of a sudden recently it left me stranded at work and wouldn't turn over again. It's been very cold in Minneapolis and we pulled that car several times around the parking lot but couldn't get the thing to fire by popping the clutch. I suspect it was just too cold.

I put in the new ignition switch and of course it doesn't turn over.

I looked at the starting schematic in the Bentley manual and found that about the only thing between the ignition and the starter is wiring and the electronic immobilizer module. I suspect it may not be a wiring issue since the first time it happened it wouldn't shut the car off when running.

Could it be a bad immobilizer module?
Others on the net have said that if the battery gets to low it can activate the immobilizer module... Is that correct? The battery is getting to be about 6-7 years old now so perhaps that is the problem??

On most cars, even with a bad battery it will at least try to turn the starter. Since this car isn't even trying I'm wondering if that immobilizer module switch is open. However, this still doesn't explain why it won't turn off once the car is started. That leads me to believe maybe it is an open circuit in the wiring somewhere???

I would repost this in the regular E36 section where more people will see it. This isn't an M3 specific issue.

That being said I would suspect the EWS system. There is a way to disable it, but I would recommend trying to get it all fixed instead of bypassing. The EWS system will prevent spark, so I think it could be keeping the car from jump starting.


It could also be the crankshaft position sensor, or the camshaft position sensor...

Thank You!

These cars have a safety switch located at the clutch pedal to prevent starting the car while the clutch is in the rest position. Your clutch switch may be going out. To top it off, it seems like you also have a key cylinder issue. Leave the new cylinder in there and inspect the clutch switch (under the driver side dash) and report back.