Intermittent Charging System Fault

Discussion in 'LR4' started by churious, Jul 16, 2018.

  1. churious

    churious Full Access Member

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    Randomly this weekend our rig started having an intermittent charging system fault. The alternator was replaced about 1.5 years ago with an OEM unit. I checked the voltage and both the battery and alternator seem to be working in spec.

    Pulled codes and these are the following.

    P0A1A-87 - Generator Control Module - Missing message
    P0A1A-88 - Generator Control Module - Bus off

    After finding these codes and reading this thread, I decided to check all the wiring on the positive terminal. Everything looked great. No burnt or loose wires like he found on positive. Also checked the entire negative area and BMS. Looked good.

    I could buy a new negative cable and BMS and try that.

    Any thoughts?
     
    Last edited: Jul 16, 2018
  2. mbw

    mbw Full Access Member

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    Those codes don't trigger a check engine light or a message in the console do they?
     
  3. churious

    churious Full Access Member

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    Yes they actually do. They trigger the "Charging System Fault" with battery icon in RED on dash. At this point im actually suspicious its the Generator itself. Its barely over a year old so I have my indy contacting Denso.
     
  4. mbw

    mbw Full Access Member

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    Yep, could just be the controller on the alternator, not pumping out enough amps as expected, etc. It's pretty simple to swap out yourself if you are ok to DIY things.
     
  5. churious

    churious Full Access Member

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    Ya, totally 3 bolts I think. It's more annoying than anything as it went down in a snowstorm last year and I didn't have time to swap it so I paid my Indy. Barely 15 months later its acting up.
     
  6. churious

    churious Full Access Member

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    Swapped alternator. Problem still exists.

    Pulled codes again. The same. Remedy via LR manual is.

    P0A1A- 87 - Generator Control Module - Missing message - Generator to engine control module LIN circuit open circuit

    • Check for good/clean contact at generator and engine control module LIN circuit connectors/pins
      Refer to the electrical circuit diagrams and check generator circuit for open circuit
      Check for engine control module hardware DTCs and refer to relevant DTC index
      Clear DTCs and repeat automated diagnostic procedure using the manufacturer approved diagnostic system




     
    Last edited: Aug 6, 2018
  7. churious

    churious Full Access Member

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    UPDATE!

    Finally figured this out after months of the error and charging issues.

    Step 1. Replaced Denso alternator under warrantee.
    Step 2. Had my indy update the ECU firmware and got my Interstate battery swapped out under warrantee.

    All together that cured the issue. Its seems that the battery (3 years old) was damaged and there was a software update to fix this for the ECU. Newer scan tools have the ability to now update outside of LR dealers which is nice.

    Just glad to have her back on the road and operational after a simple but annoying issue.
     
    cperez likes this.
  8. Travis

    Travis Member

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    Churious,

    Could you help me understand the solution a little bit better? I have a 2011 LR$ with 86,000 miles. About 11 months ago my Interstate battery failed, what I later found was probably due to the alternator. I removed the alternator and had it rebuilt. Interstate let me purchase an AGM at a reduced price from them (prorated). I didn't do anything as far as telling the ECU what kind of battery I had or anything - the previous battery was an Interstate non-AGM.

    My vehicle seemed to charge and run fine up until about 2 months ago. At that point the battery didn't seem to be charging. Interstate said the AGM battery was fine, and the test of the charging system was fine they said. I can trickle charge my battery using a battery charger and then the vehicle will start up and run well. But it will only last a couple days it seems and then it won't start. It seems that the alternator isn't charging the battery itself.

    Could you help me understand what you mean by updating the ECU firmware?

    Can I just get a different controller for the alternator or do I need a whole new alternator? The dealership said I should only use LR alternators, but those are $$. Swapping it out is fairly easy, I just don't want to purchase a new one if I don't need to.

    I don't get any dashboard lights, other than the "Battery Low; Start Engine" text in the dash info screen.


    Travis
     
  9. churious

    churious Full Access Member

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    My indy said there was a software/firmware update for the ECU and battery managment control. Thats litterally all I know. I replaced the alternator with a Denso which is the OEM alternator. It seems the system fried my other battery which may be what its doing to yours but im not 100% sure.
     
  10. Travis

    Travis Member

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    Thank you for the quick reply. I guess I'll ask the Land Rover dealership if there is a software/firmware update for the ECU and the battery management control.

    My previous battery was fried by the alternator about 11 months ago, which is why I had the alternator rebuilt and had to put in a replacement Interstate AGM battery.
     

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