Nightmare 2000 2.3 Z3 electrical issue

[Jp000z3]

I have a nightmare issue with my 2000 2.3 Z3 I purchased a few months back.

It was running great until about a month ago when I came home and the battery was dead. I got it charged up and reconnected the battery to see that the instrument cluster was already lit up and the AC blowers were on (but not the radio) with no key in ignition. I go to start the car and it starts but has an extremely rough idle. If I remove the key the car continues running roughly like nothing happened. Basically, the car thinks the key is in the ignition ALWAYS.

I have tried everything I could find online: checking for a bridge in the instrument cluster, unplugging the ignition switch, unplugging the DME relays and checking fuses, and today I unplugged the entire DME with the instrument cluster still being on when battery is connected.

I am assuming there is some sort of short somewhere because the car does leak and was parked outside for a few months before I bought it. I removed the entire interior trying to find any obvious wire damage but haven’t seen anything yet. There was about an inch of water on the floor and the foam on the carpet was soaked when I removed it. Airbag crash sensors have obvious corrosion. I did find that removing fuse 34 shuts off the DME fan and instrument cluster and 23 shuts off the DME fan and some of the lights on the cluster. Both fuses are labeled as ‘Connector for optional extras’ although 23 is also tagged with several other functions. I believe the car has some sort of aftermarket locking system because it makes a very unique chirp when locking/unlocking.

Has anyone seen a similar issue or have any recommendations of where to look??

 

[Duncodin]

Under the steering column around the key there's the plastic cover. Just a couple of screws to get the bottom one off IIRC. Mine's off. Just can't remember how many screws etc. Anyway. There you can see the wires into the back of the ignition barrel. Take a look . Does it look original or has somenody been fiddling. After market imobilizer or hotwired?

Potentially other things more likely but that's where I'd start because it's easy.

Next. The radio. There's two lives. One is permanently live. The other is on with ignition. I don't know about BMW but on some old british cars if the two radio lives were connected that would feed permanent live into the switched live circuit. No. it doesn't cause a short because, ultimately, both are live from the same source. But the switched.live circuit would be on permanently. t's possible that some affer market immobilizer is connected up behind there.

Next under the carpet. Is there some wierd after market tracker. Soaked. Potentially bridging between the permanent and switched live circuits.

Etc etc

 

[Pond]

I have a nightmare issue with my 2000 2.3 Z3 I purchased a few months back.

It was running great until about a month ago when I came home and the battery was dead. I got it charged up and reconnected the battery to see that the instrument cluster was already lit up and the AC blowers were on (but not the radio) with no key in ignition. I go to start the car and it starts but has an extremely rough idle. If I remove the key the car continues running roughly like nothing happened. Basically, the car thinks the key is in the ignition ALWAYS.

I have tried everything I could find online: checking for a bridge in the instrument cluster, unplugging the ignition switch, unplugging the DME relays and checking fuses, and today I unplugged the entire DME with the instrument cluster still being on when battery is connected.

I am assuming there is some sort of short somewhere because the car does leak and was parked outside for a few months before I bought it. I removed the entire interior trying to find any obvious wire damage but haven’t seen anything yet. There was about an inch of water on the floor and the foam on the carpet was soaked when I removed it. Airbag crash sensors have obvious corrosion. I did find that removing fuse 34 shuts off the DME fan and instrument cluster and 23 shuts off the DME fan and some of the lights on the cluster. Both fuses are labeled as ‘Connector for optional extras’ although 23 is also tagged with several other functions. I believe the car has some sort of aftermarket locking system because it makes a very unique chirp when locking/unlocking.

Has anyone seen a similar issue or have any recommendations of where to look??

My guess is that your DME/ ECU/ electronics have gone haywire due to a fault with your battery.
First thing is get a new battery. Letting batteries go completely flat, then recharging them rarely works, especially with modern (or fairly modern) electronics. Chances are the battery is damaged and is causing problems.
A new battery may not cure the problems if the electronics have been corrupted, but it a good, easy and cheap place to start.

 

[Jp000z3]

My guess is that your DME/ ECU/ electronics have gone haywire due to a fault with your battery.
First thing is get a new battery. Letting batteries go completely flat, then recharging them rarely works, especially with modern (or fairly modern) electronics. Chances are the battery is damaged and is causing problems.
A new battery may not cure the problems if the electronics have been corrupted, but it a good, easy and cheap place to start.

I have tried a new battery and also tried unplugging everything from the ECU. Unfortunately the car still thinks it’s on after both so I don’t think the issue is caused by the computer

 

[Jp000z3]

Under the steering column around the key there's the plastic cover. Just a couple of screws to get the bottom one off IIRC. Mine's off. Just can't remember how many screws etc. Anyway. There you can see the wires into the back of the ignition barrel. Take a look . Does it look original or has somenody been fiddling. After market imobilizer or hotwired?

Potentially other things more likely but that's where I'd start because it's easy.

Next. The radio. There's two lives. One is permanently live. The other is on with ignition. I don't know about BMW but on some old british cars if the two radio lives were connected that would feed permanent live into the switched live circuit. No. it doesn't cause a short because, ultimately, both are live from the same source. But the switched.live circuit would be on permanently. t's possible that some affer market immobilizer is connected up behind there.

Next under the carpet. Is there some wierd after market tracker. Soaked. Potentially bridging between the permanent and switched live circuits.

Etc etc

I did find that there was a LoJack GPS tracker installed and I have removed it but it didn’t solve the issue. I’m not seeing anything that looks aftermarket under the drivers side (immobilizer etc)

 

[NZ00Z3]

Have you checked the continuity through the ignition switch in each key position?

 

[Pond]

Sounds like a problem with the ignition switch then. Have you tried unplugging the ignition switch connector under the steering column while the car is running?
It's the furthest right one of three attached to a bracket on the left underside of the column. The other two connectors are for the left and right control stalks on the column.

 

[Jp000z3]

Sounds like a problem with the ignition switch then. Have you tried unplugging the ignition switch connector under the steering column while the car is running?
It's the furthest right one of three attached to a bracket on the left underside of the column. The other two connectors are for the left and right control stalks on the column.

Yeah ignition switch was one of the first things I checked. Unplugging doesn’t solve the issue but I did find that the female plug is getting 12 Volts to the red and green wires when no key is inserted. From what I was reading the green one shouldn’t be hot

 

[Pond]

The ignition switch actually has 6 wires. It has permanent live, accessory (radio), power to everything and start.
It also has two small wires which after much research seem to be live only with the ignition off. The consensus is that these are for either side parking lights via the indicator stalk.

So with the ignition off, you should have one big wire and the two smaller ones live.

Sorry can't remember what colours do what, even though I have a Z3 ignition switch in front of me!

 

[Jp000z3]

I found the issue! There was this ‘optional accessory’ plug under the drivers side carpet and it was severely corroded. I knew to look for it after examining the electrical diagrams for fuse 34 which is hot at all times. The corroded plug had bridged the two wires and was somehow back feeding power into fuse 23 which was only supposed to be powered when running. I cut the wire out and everything works as good as new!