Electrical problem on my Z4M Coupe ?

Nirvana1381 · 09-22-2016, 11:45 AM

Hi guys,

I'm new here and I drive a Z4M Coupe that has a bit more that 70k miles on it.
A couple weeks ago something weird happened. While I was driving on the freeway, the ABS, Brake and ASC lights came on for like 30 seconds then went away. I read the forums and assume this is a speed sensor on the rear wheels that is dirty, but I don't get to fixing it right away. About a week later, same scenario only at the end the brake light would turn red and then disappear. I checked my brake fluid and it is very very full (past maximum). I need to drain some of it out and I assume this is what the problem is, again not a big deal.
However today something else happened. I was in stop and go traffic and my battery light came on very briefly then disapeared. I noticed that my car wasnt holding the idle great either. Then once again the brake, asc and abs light came on briefly, then the tire pressure sensor came blinking, then the red brake light came on, all while my car not being able to keep a good idle. I kept the revs up a bit in this stop and go traffic to see if it would go away. Then the speedo and tachometer froze ... Then 10 seconds later, everything went back to normal and the car is running great again.

Now I really wonder what the h*** is going on. Is my battery failing ? My alternator going ? What's your take on this ?

inTgr8r · 09-22-2016, 12:20 PM

Before you do anything else, get the codes read so that you properly diagnose the issue.

Calichase · 09-22-2016, 12:33 PM

Double check your battery terminals are on and tight too

Nirvana1381 · 09-22-2016, 12:34 PM

Ill get the codes read, ok. The terminals are on tight, however the negative one shows some oxidation (green-blueish).

StickMon · 09-22-2016, 12:48 PM

All manner of crazy stuff like this will happen when your battery reaches end-of-life.
If your battery is more than 4 years old, I would start with replacing it, regardless of what codes it has.
My battery died recently and I got a similar Xmas tree of lights. Codes said throttle position sensors were bad.
Luckily, there was another thread where somebody replaced their TPSs due to the same symptoms, but still had the problem.
They replaced the battery and the problem went away, so I did that first.

Carnifex · 09-22-2016, 12:53 PM

Check your alternator/voltage regulator.

Nirvana1381 · 12-06-2016, 05:51 PM

Alright, I come back a little while later. So I changed my battery because the problem was getting worse and the battery was dying. I took it to a shop to test the charging system though and everything looked fine. Alternator churns 14.2V without load, and 14.1V under load, voltage regulator does it's job.

However, the issue is not fixed. I notice sometimes that the car will not hold idle perfectly. It is hard to notice but here is how I know something is wrong. In neutral, if I rev it up to 2k and release the gas pedal, it doesnt go back to idle, it'll go lower and struggle for a sec to get back to idle. Other dead giveaway is to get the car going in first gear and let it crawl on idle, it will not hold idle and almost stall. When that happens, I stop the car and restart again and it feels fine then.

Now yesterday something else happened. I had the ABS, ASC and Red brake light come on and off when cruising in the city. It would come on for one sec, disappear for 3 sec, come back on etc. I parked the car and did some testing. In neutral at idle, it would not do it. If I pushed the gas, when reaching 2k rpm, lights would come on and I'd see my headlights flickering.
I stopped the car, let it cool down till this morning and today everything is fine again.

The shop told me my alternator was fine based on the test they ran. However I feel like there is some kind of loose connection between my alternator and the main circuit of the car that just comes on and off for some reason. This would be what killed my battery by the car switching to battery power when the connection would be bad and draining it. I believe maybe that is what happened yesterday night, battery couldn't supply enough power to the whole car when the car was not seeing the alternator power.

What do you guys think ?

StickMon · 12-06-2016, 06:05 PM

I would rig something so I could monitor the bus voltage while I drive to get some hard data.
Hopefully that will yield more clues.

antennahead · 12-06-2016, 11:16 PM

I had some similar crazy things happening, and it turned out the battery I thought was good, and only replaced 10 months ago, was actually not so good. Just recently replaced it with an O'Reilly 48 AGM that holds a strong charge for days now. Also, you stated this: "Alternator churns 14.2V without load, and 14.1V under load, voltage regulator does it's job". My car reads 14.7 at idle and 14.4 while driving. Prior to the new battery it would read similar to your readings. I ruined a good battery this time last year when my alternator went bad, and it turns out the replacement put in by my indie shop, an Interstate, wasn't holding a charge well. I've spent an assload of money on batteries in the last 18 months, but I feel good about whats in the car now. The car was driven tonight for the first time in 4 days and prior to cranking it read 12.6 V. I'm a happy camper finally.

themenacedesigns · 12-07-2016, 10:37 AM

Quote:

Originally Posted by Nirvana1381

Hi guys,

I'm new here and I drive a Z4M Coupe that has a bit more that 70k miles on it.
A couple weeks ago something weird happened. While I was driving on the freeway, the ABS, Brake and ASC lights came on for like 30 seconds then went away. I read the forums and assume this is a speed sensor on the rear wheels that is dirty, but I don't get to fixing it right away. About a week later, same scenario only at the end the brake light would turn red and then disappear. I checked my brake fluid and it is very very full (past maximum). I need to drain some of it out and I assume this is what the problem is, again not a big deal.
However today something else happened. I was in stop and go traffic and my battery light came on very briefly then disapeared. I noticed that my car wasnt holding the idle great either. Then once again the brake, asc and abs light came on briefly, then the tire pressure sensor came blinking, then the red brake light came on, all while my car not being able to keep a good idle. I kept the revs up a bit in this stop and go traffic to see if it would go away. Then the speedo and tachometer froze ... Then 10 seconds later, everything went back to normal and the car is running great again.

Now I really wonder what the h*** is going on. Is my battery failing ? My alternator going ? What's your take on this ?

This is what happened to me when my alternator was dying when I first bought my roadster at about 55k. Same lights would randomly flash and then go out like nothing ever happened. You could tell as with the radio on full blast at a red light the volume would lower but speeding along it would become louder. I would check that first.

i2ichal2dZ4M · 12-07-2016, 11:36 AM

symptoms of alternator going out. I was experiencing same. replaced alternator and I'm good to go

RossBMWZseries · 12-12-2016, 10:58 AM

Yup same here, my problem was the alternator

Nirvana1381 · 12-12-2016, 08:07 PM

Ah damn it, that thing is expensive... oh well, thanks for the help guys, Ill get that fixed.

RADRACR · 12-12-2016, 08:16 PM

Start at post #10: http://www.zpost.com/forums/showthread.php?t=1297038

To summarize, start with replacing the voltage regulator before replacing the entire alternator. You're welcome

Pretty safe to say this is a common issue and should be done as a preventative measure.

usaz4mcr8cr · 12-13-2016, 12:17 AM

Quote:

Originally Posted by Carnifex

Check your alternator/voltage regulator.

This happened to me not too long ago. Replaced the alternator.

RossBMWZseries · 12-15-2016, 05:06 PM

When I replaced mine, everywhere I found the alternator for sale was running around ~$700. I ended up finding it around $300 on carparts.com. I believe that was the website and it was OEM. Good luck!

Nirvana1381 · 03-31-2017, 01:27 PM

I just realized I never followed up here. Changed the Alternator, issue is solved.

Vanne · 03-31-2017, 07:57 PM

Thx for following up

glad it all turned out good.

xeux · 04-01-2017, 01:14 AM

Isn't it usually just the voltage regulator vs. the entire alternator?

Nirvana1381 · 04-01-2017, 10:02 AM

It probably was, but might as well replace the whole thing. I found a Valeo replacement alternator for $260 so I figured it was worth it.

elerner61 · 04-03-2017, 01:55 PM

Think I'll swap in that voltage regulator I picked up one of these (soon to be) warm days. Avoiding a "what now" moment can't be undervalued.

Hybrid · 04-03-2017, 08:21 PM

Know this is resolved but wanted to add another data point for folks in the future. Had the exact same thing with the holy trinity of lights flashing and sudden but brief loss of power. Ended up replacing just the voltage regulator in my alternator and was right as rain again. Part ran about 30 bucks and took about half an hour to swap out.

09-22-2016, 11:45 AM	#1
Nirvana1381 New Member 3 Rep 12 Posts Drives: Z4 M Coupe Join Date: Sep 2016 Location: California iTrader: (0)	Electrical problem on my Z4M Coupe ? Hi guys, I'm new here and I drive a Z4M Coupe that has a bit more that 70k miles on it. A couple weeks ago something weird happened. While I was driving on the freeway, the ABS, Brake and ASC lights came on for like 30 seconds then went away. I read the forums and assume this is a speed sensor on the rear wheels that is dirty, but I don't get to fixing it right away. About a week later, same scenario only at the end the brake light would turn red and then disappear. I checked my brake fluid and it is very very full (past maximum). I need to drain some of it out and I assume this is what the problem is, again not a big deal. However today something else happened. I was in stop and go traffic and my battery light came on very briefly then disapeared. I noticed that my car wasnt holding the idle great either. Then once again the brake, asc and abs light came on briefly, then the tire pressure sensor came blinking, then the red brake light came on, all while my car not being able to keep a good idle. I kept the revs up a bit in this stop and go traffic to see if it would go away. Then the speedo and tachometer froze ... Then 10 seconds later, everything went back to normal and the car is running great again. Now I really wonder what the h*** is going on. Is my battery failing ? My alternator going ? What's your take on this ?
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09-22-2016, 12:20 PM	#2
inTgr8r Lieutenant General 2426 Rep 11,667 Posts Drives: M2 Comp Join Date: Mar 2006 Location: Toronto iTrader: (10)	Before you do anything else, get the codes read so that you properly diagnose the issue. __________________ '21 M2C Hockenheim Silver '18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold)
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09-22-2016, 12:33 PM	#3
Calichase Lieutenant 105 Rep 404 Posts Drives: '07 s/c'd Z4MC '08 e82 '02 m3 Join Date: Feb 2013 Location: Orlando, FL iTrader: (0)	Double check your battery terminals are on and tight too
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09-22-2016, 12:34 PM	#4
Nirvana1381 New Member 3 Rep 12 Posts Drives: Z4 M Coupe Join Date: Sep 2016 Location: California iTrader: (0)	Ill get the codes read, ok. The terminals are on tight, however the negative one shows some oxidation (green-blueish).
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09-22-2016, 12:48 PM	#5
StickMon My other car is on Mars 636 Rep 3,124 Posts Drives: 2006 MR Join Date: Feb 2011 Location: Lo-Cal iTrader: (1)	All manner of crazy stuff like this will happen when your battery reaches end-of-life. If your battery is more than 4 years old, I would start with replacing it, regardless of what codes it has. My battery died recently and I got a similar Xmas tree of lights. Codes said throttle position sensors were bad. Luckily, there was another thread where somebody replaced their TPSs due to the same symptoms, but still had the problem. They replaced the battery and the problem went away, so I did that first. __________________ Warning: May contain traces of nuts.
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09-22-2016, 12:53 PM	#6
Carnifex New Member 10 Rep 16 Posts Drives: Z4M Coupe Join Date: Nov 2015 Location: Virginia iTrader: (0)	Check your alternator/voltage regulator.
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12-06-2016, 05:51 PM	#7
Nirvana1381 New Member 3 Rep 12 Posts Drives: Z4 M Coupe Join Date: Sep 2016 Location: California iTrader: (0)	Alright, I come back a little while later. So I changed my battery because the problem was getting worse and the battery was dying. I took it to a shop to test the charging system though and everything looked fine. Alternator churns 14.2V without load, and 14.1V under load, voltage regulator does it's job. However, the issue is not fixed. I notice sometimes that the car will not hold idle perfectly. It is hard to notice but here is how I know something is wrong. In neutral, if I rev it up to 2k and release the gas pedal, it doesnt go back to idle, it'll go lower and struggle for a sec to get back to idle. Other dead giveaway is to get the car going in first gear and let it crawl on idle, it will not hold idle and almost stall. When that happens, I stop the car and restart again and it feels fine then. Now yesterday something else happened. I had the ABS, ASC and Red brake light come on and off when cruising in the city. It would come on for one sec, disappear for 3 sec, come back on etc. I parked the car and did some testing. In neutral at idle, it would not do it. If I pushed the gas, when reaching 2k rpm, lights would come on and I'd see my headlights flickering. I stopped the car, let it cool down till this morning and today everything is fine again. The shop told me my alternator was fine based on the test they ran. However I feel like there is some kind of loose connection between my alternator and the main circuit of the car that just comes on and off for some reason. This would be what killed my battery by the car switching to battery power when the connection would be bad and draining it. I believe maybe that is what happened yesterday night, battery couldn't supply enough power to the whole car when the car was not seeing the alternator power. What do you guys think ?
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12-06-2016, 06:05 PM	#8
StickMon My other car is on Mars 636 Rep 3,124 Posts Drives: 2006 MR Join Date: Feb 2011 Location: Lo-Cal iTrader: (1)	I would rig something so I could monitor the bus voltage while I drive to get some hard data. Hopefully that will yield more clues. __________________ Warning: May contain traces of nuts.
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12-06-2016, 11:16 PM	#9
antennahead Captain 73 Rep 820 Posts Drives: 2007 Z4MR silver grey Join Date: Feb 2011 Location: Charleston, South Carolina iTrader: (0) Garage List 2007 Z4 M Roadster [5.00]	I had some similar crazy things happening, and it turned out the battery I thought was good, and only replaced 10 months ago, was actually not so good. Just recently replaced it with an O'Reilly 48 AGM that holds a strong charge for days now. Also, you stated this: "Alternator churns 14.2V without load, and 14.1V under load, voltage regulator does it's job". My car reads 14.7 at idle and 14.4 while driving. Prior to the new battery it would read similar to your readings. I ruined a good battery this time last year when my alternator went bad, and it turns out the replacement put in by my indie shop, an Interstate, wasn't holding a charge well. I've spent an assload of money on batteries in the last 18 months, but I feel good about whats in the car now. The car was driven tonight for the first time in 4 days and prior to cranking it read 12.6 V. I'm a happy camper finally.
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12-07-2016, 11:36 AM	#11
i2ichal2dZ4M Lieutenant 63 Rep 516 Posts Drives: 2007 BSM Z4MC Join Date: Mar 2011 Location: Los Angeles, California iTrader: (1)	symptoms of alternator going out. I was experiencing same. replaced alternator and I'm good to go __________________ 2007 BSM Z4M Coupe - 18" VOLK TE37 - 18" Apex ARC-8 - GC Track/Street
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12-12-2016, 10:58 AM	#12
RossBMWZseries Major 224 Rep 1,130 Posts Drives: '11 E92 328i LCI & '06 Z4MR Join Date: Jun 2014 Location: San Juan TX iTrader: (1) Garage List 2006 BMW Z4M Roadster [7.00]	Yup same here, my problem was the alternator
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12-12-2016, 08:07 PM	#13
Nirvana1381 New Member 3 Rep 12 Posts Drives: Z4 M Coupe Join Date: Sep 2016 Location: California iTrader: (0)	Ah damn it, that thing is expensive... oh well, thanks for the help guys, Ill get that fixed.
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12-12-2016, 08:16 PM	#14
RADRACR Captain 84 Rep 924 Posts Drives: '08 Z4 M Coupé // '09 X5 d Join Date: Apr 2010 Location: Sioux Falls, South Dakota iTrader: (2)	Start at post #10: http://www.zpost.com/forums/showthread.php?t=1297038 To summarize, start with replacing the voltage regulator *before replacing the entire alternator. You're welcome Pretty safe to say this is a common issue and should be done as a preventative measure. __________________ '08 Z4 ///M Coupé* (#1765/1815) — 1 of 68 Sepang Bronze / Black Nappa / Madeira Wood / 1 of 1 this combo 19" Advan RS / AP Racing / Bridgestone RE-11 / Autosolutions SSK / R.E. Diablo / R.E. trans mounts '09 X5 35d — Space Grey / Saddle Brown 20" Forgestar F14 / SCR Delete Last edited by RADRACR; 12-13-2016 at 12:38 PM..
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12-15-2016, 05:06 PM	#16
RossBMWZseries Major 224 Rep 1,130 Posts Drives: '11 E92 328i LCI & '06 Z4MR Join Date: Jun 2014 Location: San Juan TX iTrader: (1) Garage List 2006 BMW Z4M Roadster [7.00]	When I replaced mine, everywhere I found the alternator for sale was running around ~$700. I ended up finding it around $300 on carparts.com. I believe that was the website and it was OEM. Good luck!
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03-31-2017, 01:27 PM	#17
Nirvana1381 New Member 3 Rep 12 Posts Drives: Z4 M Coupe Join Date: Sep 2016 Location: California iTrader: (0)	I just realized I never followed up here. Changed the Alternator, issue is solved.
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03-31-2017, 07:57 PM	#18
Vanne Down Under!! 1621 Rep 4,294 Posts Drives: 2007 Z4MC Join Date: Mar 2013 Location: Dubai iTrader: (4)	Thx for following up glad it all turned out good.
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04-01-2017, 01:14 AM	#19
xeux Private 6 Rep 85 Posts Drives: 2018 F80 M3 ZCP 6SPD Join Date: May 2010 Location: Arizona iTrader: (0)	Isn't it usually just the voltage regulator vs. the entire alternator?
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04-01-2017, 10:02 AM	#20
Nirvana1381 New Member 3 Rep 12 Posts Drives: Z4 M Coupe Join Date: Sep 2016 Location: California iTrader: (0)	It probably was, but might as well replace the whole thing. I found a Valeo replacement alternator for $260 so I figured it was worth it.
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04-03-2017, 01:55 PM	#21
elerner61 Major 157 Rep 1,107 Posts Drives: '07 Z4M Roadster Join Date: May 2011 Location: Mount Kisco, NY iTrader: (0)	Think I'll swap in that voltage regulator I picked up one of these (soon to be) warm days. Avoiding a "what now" moment can't be undervalued.
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04-03-2017, 08:21 PM	#22
Hybrid New Member 7 Rep 26 Posts Drives: BSM Z4M Coupe Join Date: Feb 2011 Location: Atlanta, GA iTrader: (0)	Know this is resolved but wanted to add another data point for folks in the future. Had the exact same thing with the holy trinity of lights flashing and sudden but brief loss of power. Ended up replacing just the voltage regulator in my alternator and was right as rain again. Part ran about 30 bucks and took about half an hour to swap out.
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