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Thread: intermittently charging issue

  1. #1
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    intermittently charging issue

    I have a weird charging issue and I am looking for some help.

    Sometimes while I drive, the car will not charge the battery at all, meaning that I am just discharging the battery which can lead to the complete stop and shut down of the car. When this happens, if I wait 10-15 minutes, I can restart the car and car will be charging the battery as if nothing were wrong. When this happened first a few month ago, I changed the battery (it was time to change), but it happened again twice yesterday.

    Any recommendation where to start?

    Thanks,

    Vadim
    '10 750Li 130K
    -----------------------------------------
    Vadik

  2. #2
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    Your alternator only charges when the car is coasting. Yes, I know, that's stupid.

    Does your oil level sender work? Can you check the oil via the I-drive? (Yes, I know that sounds unrelated, but it's not)

    Read this:

    https://www.roadandtrack.com/car-cul...ns-bmw-n63-v8/

    Never mind the charging -- you should really get rid of this car quickly, before you need an engine. The N63 generally doesn't last 100 k miles.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

  3. #3
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    Quote Originally Posted by bmwdirtracer View Post
    Your alternator only charges when the car is coasting. Yes, I know, that's stupid.

    Does your oil level sender work? Can you check the oil via the I-drive? (Yes, I know that sounds unrelated, but it's not)

    Read this:

    https://www.roadandtrack.com/car-cul...ns-bmw-n63-v8/

    Never mind the charging -- you should really get rid of this car quickly, before you need an engine. The N63 generally doesn't last 100 k miles.
    It is either charges all the time (consistent 13.9V under any load and RPM/coasting) or not at all, for whole ride, so I am guessing, it is somewhere in the electronics. oil level works, and no errors shown by ISTA.
    -----------------------------------------
    Vadik

  4. #4
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    The alternator (and the oil level sender) are controlled by the BSD bus circuit. This bus has a single wire connecting all 3 components: alternator, oil level sender, and DME.

    The alternator is not supposed to charge 13.9 V all the time, as you'll have seen in the R&T article. I'd GUESS that you have a BSD fault. Certainly, though, if the BSD circuit has an issue, OR if the alternator stops charging at any time without being commanded to stop charging, codes should be instantly set, which ISTA should find, and develop a test plan to diagnose.

    We had an identical car to yours in the shop, for a replacement engine, at 65 k miles. After the engine replacement, the car had a BSD code. ISTA said "Check these bolts", with a picture. Sure enough, one of the bolts, which ground the wiring rail on each cylinder head, was missing. That killed a ground inside the DME. However, the alternator continued charging...at 13.8 volts continually.

    Certainly, you should check the plug with the small single violet wire at the back of the alternator; make sure it's properly clipped on. Also, check the main big hot lead at the alternator, and at the starter, and at the B+ terminal underhood, Then also check both battery terminals, and the main engine ground wire. If any of these connections are loose, the battery won't get charged

    Do you have a red battery warning light when the alternator suddenly stops charging? What exactly is your signal that tells you the alternator's not charging?

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

  5. #5
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    Thank you,

    I'll definitely will check bolt and wires.

    To see if it charging or not I am using ODBII info (ODB Fusion app) to monitor voltage, when it is charging, it is 13.9 (+-.1)V otherwise it is below 12 V and consistently going down to about 10.4V before car shuts off. There were no codes in ISTA last time I tried, but I'll check wires and try again.

    Vadim
    -----------------------------------------
    Vadik

  6. #6
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    I may be getting somewhere.

    Yesterday on the way home, car died on high way, I waited 10 min, restarted car and drove home no problem. Today I went to trouble shoot. Started the car, run ISTA got 58 errors from yesterday shutdown, deleted fault memory, restarted the car, run ISTA, nothing as usual but voltmeter was showing 14+V, so car was charging. Locked the car, waiting 15 min, started the car, Voltmeter was showing 12.1V and slowing going down (i.e. no charging), run ISTA got two BSD errors (see https://imgur.com/a/opF5k8L).

    Recommendations at this point?


    Can not upload the image but errors are:
    210901; BSD, message; alternator: Missing
    CD9304 BSD data bus Communications fault
    Last edited by kutsyy; 01-12-2019 at 08:59 PM.
    -----------------------------------------
    Vadik

  7. #7
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    Follow the ISTA test plan.

    Bottom right: Calculate test plan. Your version is a little different from mine, but when the test plan comes up, double click on the top fault, follow through with test plan for that item.

    I'm wondering about the ZGM (central control module) lack of initialization, too.

    The car isn't finding the alternator. You're also not showing voltage at top right on terminals 15 and 30. What sort of weird clone ISTA are you using? Do you have a good stable power supply on the car while you're using ISTA? You need 13.4 to 14.9 volts!

    Have you checked whether the violet wire is firmly plugged into the alternator? (It can get to looking brown, after eight years living between cats and turbos)

    There are only 3 things on that wire: Alternator, DME, and oil level sender. You could check that wire for voltage, too; should be battery voltage,

    Have you had any work done to the engine, before this started?

    Any chance someone left a bolt loose on the wiring rail?
    Last edited by bmwdirtracer; 01-12-2019 at 09:22 PM.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

  8. #8
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    it is not "BMW approved" ISTA , downloaded from https://www.bimmerfest.com/forums/sh...1#post10521394 and at the time of the test, it was running from the battery only (12V).

    I'll go through all the wires and connectors tomorrow, if someone forgot to tighten anything, it would be me, I replaced turbo oil return gasket about a year ago.

    Thanks for your help.
    -----------------------------------------
    Vadik

  9. #9
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    Do I call you Vadik, or Valim?

    There are three e-torx bolts on each head, holding down and grounding the wiring loom. Some damned dumb ass at BMW thought it would be okay for those to be crucial grounds. If just one of those bolts is left out, or loose, the damned DME gets fried.

    Now, this may not be the case, with your car...MAYBE the alternator plug is just loose?

    All that said, I really think that someone with an I.Q. equivalent to his shoe size designed the BSD circuit.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

  10. #10
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    Chris,

    you can call me Vadim or Vadik, either works.

    The e-torx bolts you are talking about are shown on https://www.newtis.info/tisv2/a/en/f...ces/1VnXWbuNNz, right? Since charging sometimes works, I hope that nothing is fried, and it is just a loose connection somewhere.

    Thanks,
    -----------------------------------------
    Vadik

  11. #11
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    Yep; those are the deadly bolts. I'm sure that BMW found this out quite by accident, after a number of DME's were toasted. Seriously, who would design something like that? Maybe they could have at least put yellow warning labels, like they do for everything else?

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

  12. #12
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    Chris, got a few updates,

    My understanding that these 3 screws are on the left (passenger) side. They look very good, I double checked, very nicely tighten.

    The brown wire is on the back top of the alternator, right? It was plugged in. I unplugged and connection seems good. The wire has insulation broken in one of the places (see last photo), but I don't think it matters, thoughts?

    Photos: https://imgur.com/a/5uHmTvP

    Thanks,
    Attached Images Attached Images
    Last edited by kutsyy; 01-13-2019 at 03:43 PM.
    -----------------------------------------
    Vadik

  13. #13
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    As you'll see in the TIS link, these crucial bolts are on BOTH sides - look at the second picture in TIS.

    I know that wire LOOKS brown, but that's just because the violet color got burned away by the intense heat of having cats and turbos in the center of the "V".

    Any chance that someone has already been hunting for this problem? Because that break in the insulation sure looks like someone's been stabbing with a dull probe.

    Can you follow through the ISTA test plan for the 2 BSD codes?

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

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