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      11-16-2016, 09:19 PM   #1
bdn3d
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Car is acting up, see photo below. Speedometer isn't working, looses power over 5k rpm and seems to be an electrical issue. I took it by my local shop and they ran a diagnostic test on it and they said it looked like it was just blow voltage on cranking amps on the battery, but the battery is less than 1yr old and so is the alternator.

They tried to clear the codes and were unsuccessful then I was told it was a steering sensor. It's a new guy there so the info could have been wrong what do you guys think?

Oh one more thing we just had our first cold front, which is really not that because we are in Florida, it may have gotten down to 50 but it just seems that every year around this time I have to replace a battery or something because the car doesn't like the cold...
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      11-16-2016, 11:12 PM   #2
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The tech may well be correct about the steering angle sensor. It's one of the digital devices on the K bus and if it gets hung up all of the data to and from the Instrument Cluster is either corrupted or frozen. My car did the same thing two years ago and it was the SAS. Fortunately reprogramming it got it functional again and there's been no further issue to date. This document on the BMW digital busses may help with understanding the issue.
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      11-16-2016, 11:16 PM   #3
bdn3d
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The tech may well be correct about the steering angle sensor. It's one of the digital devices on the K bus and if it gets hung up all of the data to and from the Instrument Cluster is either corrupted or frozen. My car did the same thing two years ago and it was the SAS. Fortunately reprogramming it got it functional again and there's been no further issue to date. This document on the BMW digital busses may help with understanding the issue.
Thank you, what would lead to the loss of power?
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      11-17-2016, 06:04 AM   #4
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When you've got one of the items on one of the digital busses hanging the bus or corrupting the data behavior is unpredictable, so loss of power isn't out of the question. When mine acted up the instant the lights came on in the instrument cluster it started running rough, had a very rough idle and felt a bit down on power even at lower rpm. The turn signals were erratic, the radio controls on the steering wheel were unresponsive, and even the controls on the face of the radio only had minimal control. There may have been more issues but I only had to drive the car a short distance from where the problem surfaced back to the dealer.

The local dealer was offering $79 oil changes and since that's almost the cost of the oil and filter to do it your self I jumped on it. I had left and was about a mile away and when I accelerated away from a traffic light the dashboard lit up. I had to go a mile or so to get turned around and back, but even in that short time you can see all the things I saw that had gone wonky. Normally I would have limped home and worked on it myself at least initially, but I was leaving on a ploanned 3K mile road trip the next day and needed the car fixed ASAP.
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      11-17-2016, 06:39 PM   #5
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Update... this morning it took 3 cranks to get the car started, never don't that before. Then I had intermittent issues with battery and light coming on and off which also shuts off rpm meter. This is happening while at idle and under throttle.

Seems to be getting worse?? :
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      11-18-2016, 09:45 PM   #6
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I had similar symptoms when my alternator was going out. My money is on bad alternator. I had my alternator replaced and a faulty unit was put in, it does happen.

Did the shop test the alternator? If not, do you know how to check the alternator voltage from the dash?
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      11-19-2016, 03:25 PM   #7
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Quote:
Originally Posted by tiltmode43 View Post
I had similar symptoms when my alternator was going out. My money is on bad alternator. I had my alternator replaced and a faulty unit was put in, it does happen.

Did the shop test the alternator? If not, do you know how to check the alternator voltage from the dash?
Do not know how to do that in sure I can find that on YouTube?

Here is a quick video of what's happening.

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      11-21-2016, 01:24 PM   #8
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Do not know how to do that in sure I can find that on YouTube?

Here is a quick video of what's happening.
You've definitely got something messing with the digital busse(s) going on there!

Here's a video that shows how to access the instrument cluster test menus, and link to a thread that lists what all the different test modes do.

http://www.bimmerforums.com/forum/sh...es-in-your-car!

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      11-21-2016, 02:49 PM   #9
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Quote:
Originally Posted by bdn3d View Post
They tried to clear the codes and were unsuccessful then I was told it was a steering sensor.
ok.....what codes?

Hook it up to an ista-d machine (or DIS/SSS) and see what modules it can communicate with and which not.
This is not a steering angle sensor issue I think...
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      11-21-2016, 10:42 PM   #10
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Quote:
Originally Posted by GuidoK View Post
Quote:
Originally Posted by bdn3d View Post
They tried to clear the codes and were unsuccessful then I was told it was a steering sensor.
ok.....what codes?

Hook it up to an ista-d machine (or DIS/SSS) and see what modules it can communicate with and which not.
This is not a steering angle sensor issue I think...
I think it's important to add that now it's officially draining the battery while parked and off... I got the battery tested and fully charged they said it was good. Put it back in car yesterday and I just tried to crank it and completely dead... I'm going out of town for thanksgiving so I'll have to revisit this next week but I'm really worried this isn't something major...
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      11-21-2016, 10:55 PM   #11
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That you were able to crank it and the meters got all wonky is to me a sign that its not the battery or the alternator. Unless the altenator gives way to high voltage and fried a cpu. So a voltage check is a thing to do, although the battery acts as a line stabilizer (basically a very big capacitor).
Normally when the voltage drops the car wont crank, but you wont see these strange things imho.
The cranking also doesnt sound like a weak battery.

So I think a module is fried/playing up and using current.
That its using current makes it easier to detect; do a current draw and unplug fuses one at the time.

If you're not into automotive electronics it'll be unlikely that you can fix this problem without the help of a specialist onsite.
The instrument cluster is afaik connected within both the I/K-bus communication as the CAN bus communication (they are seperate networks in the car), but that means that virtually all modules can interfere with information going through the instrument cluster.
(although the indicators/meters that move and flicker are all CAN related)
It can also sit in the wiring (lets hope not...)
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Last edited by GuidoK; 11-21-2016 at 11:14 PM.
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      11-23-2016, 11:58 AM   #12
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Quote:
Originally Posted by tiltmode43 View Post
I had similar symptoms when my alternator was going out. My money is on bad alternator. I had my alternator replaced and a faulty unit was put in, it does happen.

Did the shop test the alternator? If not, do you know how to check the alternator voltage from the dash?
same issue I had when my alternator was dying.

I would have this looked at.
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