Dash Lit, Head Unit In And Out, Z4 Stranded

[TitanUcheze]

Hey all,

I’m currently experiencing some electrical issue with my Z4. Within the past month or so, I have replaced the battery, starter, and finally the alternator, in that order. The old battery was ~7 years old, and the alternator I had bench tested and confirmed to be bad. After replacing the alternator 2-3 weeks ago, the car has been running perfectly and issue-free.

Today on my way home from work, several yellow warning lights (tire pressure, ABS, DSC, etc) came on, and my head unit kept dying and then coming back on. I was able to get home, and switched the car off. An hour later I came out and it started up, and the lights were gone, but not 15 minutes into my drive all of the lights came right back on, as shown in the video below, so I pulled over and my car sputtered and died. Speedo stayed at 40 mph, tachometer showed ~2.5K revs and froze, even when the car was off and I had stopped. I took two short videos, and turned the car off. It refused to start again, so I went and measured the battery voltage immediately, and it measured 11.54V. A dead battery, which would explain the issues I’m having, so my plan is to pull the battery and have autozone bench test it tomorrow, if it’s bad I can have it replaced under warranty.

Any other ideas based on the videos below?

[TitanUcheze]

Here are a few clips of what happened. In the second, you can see the lights flickering dimmer and brighter along side the hazards flashing. The car completely shut down after about 45 seconds of hazards. I tried to jump it, and it started and ran for around 30 seconds before dying out with all the lights coming right back. After that, no jumping would help. I suspect a rubbish battery (I've replaced the battery, starter, and then alternator around 3 weeks ago and it's run perfectly since replacing the alternator until now).





Thoughts?

[psycleridr]

I would check battery first being that you replaced it prior to the alternator. This may have drained it excessively to the point where the new alternator cant recharge it.
These cars tend to throw all kinds of lights and codes when voltage is low.
Start there and let us know

[TitanUcheze]

That's my thinking, I'm going to pull it and have it bench tested this afternoon.

[dbarton62]

Lots of posts on lots of forums regarding electrical gremlins.
I chased mine for almost a year before I dug into the grounding bar behind the dash above the fuse panel.

https://www.bimmerforums.com/forum/s...e-they-related
https://www.zpost.com/forums/showthread.php?t=1412214

[TitanUcheze]

Lots of posts on lots of forums regarding electrical gremlins.
I chased mine for almost a year before I dug into the grounding bar behind the dash above the fuse panel.

https://www.bimmerforums.com/forum/s...e-they-related
https://www.zpost.com/forums/showthread.php?t=1412214

By far the worst kind of issue to address on a vehicle. I checked both threads and read the post on the guys website. I'm not opposed to digging into that, but the symptoms he listed were not really what I was experiencing. I have experienced the same issue that I am experiencing now, a few weeks ago, and it was because the alternator was not feeding the battery the necessary charge, so the battery was dangerously low. Hence my reasoning for perhaps the battery being bad/fried, with the voltage being inconsistent (voltage regulator was toast) and the battery really struggling for a few weeks after being replaced due to that issue. I'll report back this evening with more details, and maybe hook up the INPA software to see if any errors are being thrown.

[dbarton62]

By far the worst kind of issue to address on a vehicle. I checked both threads and read the post on the guys website. I'm not opposed to digging into that, but the symptoms he listed were not really what I was experiencing. I have experienced the same issue that I am experiencing now, a few weeks ago, and it was because the alternator was not feeding the battery the necessary charge, so the battery was dangerously low. Hence my reasoning for perhaps the battery being bad/fried, with the voltage being inconsistent (voltage regulator was toast) and the battery really struggling for a few weeks after being replaced due to that issue. I'll report back this evening with more details, and maybe hook up the INPA software to see if any errors are being thrown.

I also had the radio in/out before it quit totally among other gremlins.
Of course check the obvious first.
If you delve into the ground bar, take note of "stickmons" post towards the end of the Zpost thread about removing the fuse and not the ground of the culprit system.

[TitanUcheze]

Alright, so I brought the battery in to have it tested, and the battery needed to be placed on a trickle charger. After charging it up they tested it, and it tested good, with the battery at 13.01V now. The battery was flat the day the issue occurred, so next up I presume would be the alternator, as the only way the battery can go flat is if the alternator is not providing it a re-charge.

dbarton62: I looked at the thread you are referring to, and if it comes to it I can work my way through the fuses again, and if absolutely necessary checking the grounding. It doesn't look overly complicated and honestly I'm just eager to get my roadster back on the road. I'd hate to bring it into the dealer or an Indy, but if it comes to it I will, at least for a diagnosis.

Current thinking is that I should take the fully charged battery, reinstall it, and then have the alternator tested to make sure it is putting out the appropriate voltage to the battery. Aside from that and then progressing to grounds/fuses, is there anything else recommended?