Z3 won't start, no crank, no power windows

[sruchris]

Today my Z3 wouldn't start and had to be towed home. When I try to start it all of the dashboard lights come on, but it doesn't crank. All of the electronics work except for the power windows. After I try to start it the oil and parking brake dashboard lights stay on, which is odd. I swapped the battery from another car and tied to jump it and the same thing happens. I don't think it's the battery.

I checked the fuses and they are all good. Over the last few years, I have several related problems:

1) One out of twenty times my key won't turn when trying to start the car. A little wiggle resolves this problem.

2) The soft top open/close switches sometimes are wonky. I need to press the brake pedal several times for the switch to work (I think it's the brake switch)

Any thoughts? Could it be a relay? Or my immobilizer?

[MIKYZZ4]

Make sure the brake and starter interlock switches on the pedal assembly are not misaligned,
causing the plungers to not depress, and also checking for clean,snug, electrical connections.
Diagram here:https://www.realoem.com/bmw/enUS/sho...diagId=35_0252

[sruchris]

I just check the alignment of both the brake light and clutch pedal switches. Both are aligned and push each button (white with a red collar) in and out correctly. When the soft top buttons don't work, my brake lights don't work as well. I've always assumed my brake light switch was going bad but it doesn't explain why the car won't start.

[jclausen]

Try another key your car has ews and if your key is really worn that could be why the ignition tumbler won't turn

[MIKYZZ4]

You can test switch by disconnecting and removing switch,
and checking resistance across the 2 contacts at the switch,
while operating plunger, using a multimeter.

[sruchris]

I thought about using another key as sometimes I have difficulties turning the key when unlocking the car door. Unfortunately, I have only one key. When I turn the key to the on position, the stereo, headlights, dome light, AC, blower fan, turn signal all work except for the power windows.

[z3forlife]

You can get a spare key from the dealer for around $70. It sounds like it's time

[Randy Forbes]

Could be unrelated, but look for and check the fusible link in the trunk, near the battery (in one of the Big Cables). On a friend's '98 M Rdstr, it really had us scratching our heads when half the car had power and the rest of it__the part that makes it go__didn't.

His had just corroded apart (immaculate, well kept Florida car all its life...)

[sruchris]

I'll pickup a new key tomorrow and check the fusable link. Would the trunk wiring cause these problems? I repaired them last weekend and all of the wiring still looks fine.
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[Vintage42]

Great looking job. So you found that some wires were frayed or broken?
I don't they would cause the dashboard and windows problems you mention in Post #1.

[sruchris]

Great looking job. So you found that some wires were frayed or broken?
I don't they would cause the dashboard and windows problems you mention in Post #1.

Thanks. Yes, all but two were frayed.

[sruchris]

Try another key your car has ews and if your key is really worn that could be why the ignition tumbler won't turn

A new key will take a few days from dealer. Can I remove the ignition switch, insert the key into ignition (for EWS to be happy) and turn the ignition switch by hand with a screwdriver?

[sruchris]

So I tried turning the ignition switch by hand while the key was turned in the ignition. Still no crank. I then checked the voltage on the positive jump post under the hood. It read 0 volts. The battery read 12.2 volts and my other car started fine when I put this battery in it. Maybe it is the fusable link. I guess I'll tear into these red cables.

[me77]

I'm not sure, but does a MY2000 have a battery safety terminal?

[sruchris]

I'm not sure, but does a MY2000 have a battery safety terminal?

Yes, my car has a battery safety terminal that immediately runs into a 200 amp "mega" fuse. On a related note, my passenger's airbag light has been on since I bought the car 3 years ago.

[sruchris]

I'm not sure, but does a MY2000 have a battery safety terminal?

Does anyone know where the other end of the BST connects in the Z3? Is it under the passenger's seat? I'd like to check for voltage and/or corrosion at this connection before I spend $250 on a new BST cable.

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