NS rear light staying on (E85 Z4)

Ben Cole

Ben Cole

Ben Cole

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Walked past the Z parked up on my drive earlier and noticed illumination from the NS rear light.

Not fully illuminated but definitely "on".

At first I thought it was the parking light but it wasn't.

I took it for a drive and everything works fine but after parking up and locking the light remains on.

I'm thinking that with all the rain recently something is being shorted out. Disappointing build quality if so.

Has anybody had anything similar or any suggestions?

Could I get anything done under the BMW insured warranty?
 
So I take it the front sidelight is working but not on then? If so that should rule out the contacts on the stalk, first quick and easy check switch the bulbs over and clean the contacts. If you're still getting the problem trace the wiring about as far as you can and check for any obvious damage
 
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Not sure I've explained myself well enough.

The car works perfectly...except when parked up with the ignition off the NS tail light is illuminated. I cannot switch it off. When the ignition is switched on, all lights work correctly and to their normal intensity.

I have unplugged the cluster to stop the battery draining for now.
 
No I get that. First thing I wanted to check is that the front sidelight wasn't doing the same but the bulb was blown so you couldn't see. If it was it .might still have been the parking lights like you mentioned above and could have been related to your indicator stalk.

Then by swapping the two rear sidelight bulbs and cleaning up their connection your ruling out and problems at that end.

The next thing you'll probably want to do is take both rear clusters out and swap the connection so that your offside lamp is plugged into nearside ( assuming you can, the connections are usually the same) which should tell you of there's an issue with the metal tracks in the light unit itself or wiring. If the other lamp does the same you will have to start checking wiring, which is where it starts to get a bit more of an annoyance. I would look at any section where the wiring runs through a fkexi section as a first point.
 
Thanks for the input.

There's power going to the cluster when there shouldn't be also the light works properly and to the correct brightness when required so I'm thinking that it's more likely a control unit problem. I don't think the wiring passes through any flexi sections.
 
Silly question, but you've not left your indicator on have you? i.e. N/S indicator left on when ignition turned off so that the N/S lights (not indicator lights) stay on
 
Sounds like it could be but I'm not sure how you would test it. Do you have access to inpa or another bmw specific software to run the full code set? You can access the light modules and I'm sure run tests from there ( though I've only ever run cluster and engine related tests so not sure what they are)

(re)edit: should be able to check as it'll be part of the switch i guess - was being a bit dim (boom boom) before

 
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cokecan said:
Silly question, but you've not left your indicator on have you? i.e. N/S indicator left on when ignition turned off so that the N/S lights (not indicator lights) stay on
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No. As I said above it's not the parking light.

rodenal said:
Sounds like it could be but I'm not sure how you would test it. Do you have access to inpa or another bmw specific software to run the full code set? You can access the light modules and I'm sure run tests from there ( though I've only ever run cluster and engine related tests so not sure what they are)

(re)edit: should be able to check as it'll be part of the switch i guess - was being a bit dim (boom boom) before
Click to expand...

No access to anything other than a OBD reader. I was hoping the pixies had been overnight and fixed it (water drained away or dried out) but no. I also disconnected the battery for 30 mins to see if that reset anything.

Looks like I'll just have to try the stealer and see if the warranty covers it/part of it.
 
So, if you are parked up, with the ignition on, but the light switch off (ie, so all lights are off) what does this light do? Stay on, or go off? If it goes off, does it then go on when you exit the car and lock it with the remote?
 
It stayed on no matter what I did...however after another drive round it went to intermittent and now is off.

Therefore I think my suspicions look more likely and that use has dried something out. It had only been driven once in three weeks and the weather has been atrocious.

Going to go out and check it again now. Fingers crossed.
 
HELP!!!

3 Days with BMW Cardiff and they couldn't sort it. Couldn't find any water ingress or signs of anything failing.

They just shrugged and tried to blame it on the aftermarket HIDs fitted at the front.

Anyone any help? This is bad, at the moment I have to disconnect the cluster every time I park up.
 
Have you tried disconnecting the aftermarket HIDs?
I doubt it's those but an easy thing to eliminate.
 
Tesla said:
Have you tried disconnecting the aftermarket HIDs?
I doubt it's those but an easy thing to eliminate.
Click to expand...

That's my next port of call. It's also what BMW suggested they would do.

The problem there is that they'd start charging me because they are not BMW items.
 
Although it doesn't seem like it will be the problem, I'd try pulling the connection at the control unit and seeing if this cures things.

I can't really see how that would be related to the weather though. Sounds like you almost definitely have a wiring issue.

Eliminate the hids first
 
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