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  #1  
Old 06-27-2020, 11:48 AM
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Swanicyouth Swanicyouth is online now
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E85 M Roadster DSC, ABS, Brake Light Intermittent




E85 M Roadster Diag Input Wanted

I have an E85 Z4 M 3.2 S54 2008 70k miles. Occasionally Iíll be driving it and DSC, ABS, and brake light will flash on for a few seconds. Last time it happened it was about a minute & restarting eliminated the lights.

Codes:

2CFB/not present DME throttle valve adaptation not present

51E6/not present DSC no message. IKE (610. 613 or 615)

5DF7/not present DSC: system voltage too high

5DF4/not present DSC: battery voltage too low; open circuit

5 SZM: undervoltage seat heating

6 SZM undervoltage roller sunblind

Codes were erased about 1000 miles ago when misfire in cylinder 2 was repaired via new ignition coil (replaced all 6 with Bosch).

No CEL

Idle voltage about 14v. Every minute or so engine will hiccup ever so slightly and voltage drops to about 12.7v. Voltage above 2000 rpm > 14v. Not sure if voltage drop is causing hiccup or vice-versa. Other than that car drives fine.

Iím guessing intermittently bad alternator / voltage regulator assembly. Replaced factory battery about 2 years ago & car cranks / starts fine.

Codes were retrieved with a Foxwell scanner. I think itís a 510.
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  #2  
Old 06-27-2020, 08:55 PM
Andyz4 Andyz4 is offline
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What is your battery test voltage (engine off)? Should read 13.2 or better, mid-12's might start car but can trigger codes.
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Old 06-28-2020, 07:29 AM
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GeorgeT GeorgeT is offline
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Classic signs of a failing battery.
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Old 06-28-2020, 09:39 AM
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Quote:
Originally Posted by Andyz4 View Post
What is your battery test voltage (engine off)? Should read 13.2 or better, mid-12's might start car but can trigger codes.
None of the cars that had ever owned ever reads 13.2V when engine is off! Best I've seen was on my e53 that reads about 13.0V as soon as I had shut the engine off on a new oversized AGM battery that I had just installed. It didn't remain at 13.0V for long - dropping down to about 12.8V after about 10minutes and remains there for a while.

On the e86, the best that I've seen on a brand new AGM H7 (oversized) that was just installed was about 12.8V. On an AGM H6 (standard sized), my steady state voltage after charging is usually about 12.6V and this is on a new battery.

Unloaded, I can see how you would be able to obtained 13.2V after a fully charge, which is the theoretical maximum voltage that you can get from a 12V battery (assuming 2.2V per cell). But you are most likely to only get 2.15V per cell in the real world...so 12.9V is what you would get realistically from a brand new battery - unloaded.

FYI - I've seen 12.0V on my e86 on a 5 year old battery and it would still start the car without any issues (no codes triggered). But my experience is on AGM.
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Old 06-28-2020, 09:10 PM
Andyz4 Andyz4 is offline
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I stand corrected, both my Z and one of our Miatas (brand new non- AGM) tested at 12.3 v. Must be the lysdexia.
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Old 06-29-2020, 05:22 AM
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Thanks guys. Iíll have to check the bat. Itís not too old, but car cranks pretty strong after sitting a week undriven - so I was leaning more towards alternator

Bought a stick on voltage gage from Amazon I can tap into fuse box to see whatís going on with voltage when this happens.
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Old 06-29-2020, 07:21 AM
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Quote:
Originally Posted by Swanicyouth View Post
Thanks guys. I'll have to check the bat. It's not too old, but car cranks pretty strong after sitting a week undriven - so I was leaning more towards alternator

Bought a stick on voltage gage from Amazon I can tap into fuse box to see what's going on with voltage when this happens.
My bet is on the alternator if you got a voltage drop near 12.7v when the car is running. My e53 was doing that a few months prior the the alternator went kaput.

But then again, your DSC module could be acting up too as I also seen those lights when mine did died - also on my e53. However, my e53 didn't have the voltage drop issue when the DSC died - this happened a couple of years after I had my alternator replaced.
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  #8  
Old 07-02-2020, 05:04 PM
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Load tested the battery - itís ok. Pretty sure itís alternator as well. Apparently there is a DSC module rebuilder & the codes Iím getting do not apply.

Itís very easy to diagnose a bad alternator. Itís very difficult to diagnose one that just randomly stops charging for a few minutes after an hour or two of driving.

So, another question for anyone experienced with the Valeo alternators in the 3.2 M.

Itís seems the voltage regulator is externally mounted on the case & is available to purchase. Has anyone just replaced voltage regulator? Are diodes & brushes part of the assembly? If so, not much else to go wrong in this situation.
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Old 07-02-2020, 05:53 PM
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I replaced my voltage regulator more as a maintenance thing than because I had to... wasnít difficult to do. If I remember correctly as that was about 4-6 years ago, there are carbon brushes in the voltage regulator. I kept my old voltage regulator as a spare part as the brushes werenít ďthatĒ worn and the new voltage regulators output wasnít that much greater than the old regulator.


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Old 07-06-2020, 03:55 PM
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Figured out the issue. Bought a cheap voltage gauge on Amazon so I could see exactly what is going on with the charging system when these lights come on.

Turns out, first voltage spikes above 15.5v; then it drops to about 12 & flip flops in between. DSC + other lights go on & off as voltage spikes and drops out of spec.

I just ordered a new Valeo alternator w/ regulator from Rock Auto. They have brand new ones - not remans for sale for a few more dollars.
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Old 07-06-2020, 05:29 PM
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Thanks for updating us.... much appreciated.


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Old 07-09-2020, 07:52 AM
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Thanks for updating us.... much appreciated.


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Sure. Installed new Valeo alternator/regulator assembly yesterday from Rock. Fixed
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