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).

[youtube] https://www.youtube.com/watch?v=jddERv_q2U0 [/youtube]

[youtube] https://www.youtube.com/watch?v=U1bLAMH0tFE [/youtube]

Thoughts?

 

[Woots]

Hmm could be that the battery etc is fine, that’s just something shorting/dragging everything else down with it, which may have blown a fuse for speedo? Assuming there is a fuse for that but perhaps the whole instrument cluster has one...
What happens if you unplug the aftermarket head unit? Assuming it’s easy to remove?

 

[TitanUcheze]

I brought the battery in to have it tested and it tested good, you may be right that something is shorting/draining the battery. I'll go through the fuses tonight, I just had the battery trickle charged to full, and I'll pull the head unit fuse to see if that is the culprit. It is an aftermarket unit, so it could very well be the culprit. With a full battery, I should be able to tell.

 

[Wortmanov]

Did you check voltage with running engine after replacing the alternator? I know it was replaced, but could be as simple as a bad unit? Are all the cables 100% secured on the alternator?
The lights light up in the exact same way as mine a few weeks ago and that was a dead alternator.

 

[thecremeegg]

Looks 100% like a bad alternator to me - had exact same issues/symtoms on my old MX-5!

 

[Wortmanov]

Looks 100% like a bad alternator to me - had exact same issues/symtoms on my old MX-5!

+1 It is exactly what happened when my alternator went.

 

[ph001]

Yes, that’s exactly what happens when you run the car just on battery without alternator charge as the voltage slowly drops down below 12v. Should have had battery light on though?

 

[jamie_z4]

Yep goosed alternator