Alternator, Voltage Regulator and Charging Issues
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GL350 2015
Alternator, Voltage Regulator and Charging Issues
I have been working to sort out the dreaded red battery warning > See Operators Manual and hoping to not throw $$ in the wrong place.
2015 GL350
Valeo 9060903 CG25S035 alternator
Steps Taken:
1) Replace auxillary battery. I took out the tiny stock battery and put in the larger one that fills the cage. This size shows as the correct size in many searches and appears to have been installed in many GL modes from the factory.
2) Replace the 1.5 year old battery that tested as having a bad cell. (old and new main are AGM Energizer from costco H8).
3) Remove alternator and found that one of the brushes was not making contact.
4) Replaced the brushes and springs according to the following videos ($13 canadian dollars on amazon):
5) Volt meter tested the alternator according to this video
> all tests passed.
6) Reinstall alternator
7) tested continuity from negative boost post to alternator housing > all good
8) tested positive alternator post to positive boost post > all good
9) Tested voltage at alternator and it was the same low voltage as the main battery = assume alternator still not putting out proper voltage (or any?). at times the voltage seemed to jump up .25 of a volt and ranged between 11.5 and 11.8v while running on a battery with 12v of charge when the car is off.
All equipment is original except for the new brushes and batteries so far.
Result = same red warning and not charging
Possible issues?
1) maybe the brushes didn't seat properly on the slip rings. its kinda finicky to get it all together with the cap.
2) i cant imagine the solder connections on the brushes are bad, but possible?
3) can an alternator pass all voltmeter tests and still not work?
4) can there be a bad relay or fuse somewhere?
5) open to all other ideas
6) i didn't find any great video about how to bench test voltage output of the alternator with a drill or something because that would have been logical after repair to avoid the extra effort of installing a bad alternator.
i expect a bunch of comments to tell me just to buy a new alternator and this is where i'm basically at... (and wishing i started there). Im just stumped because it should work according to the above videos.
but after all my efforts i would like to have learned something. I also don't want to buy the alternator and find the problem is somewhere else.
Some argue > the alternators are over-engineered and as the brushes are wear items, just deal with the voltage regulator (which can not be easily bench tested). I hoped i found the problem when i saw one slip ring shiny and the other black, as in the videos. Still a mystery of frustration.
Others argue > why replace the voltage regulator when the alternator is next to go or already bad.
many thanks for reading!
matthew
2015 GL350
Valeo 9060903 CG25S035 alternator
Steps Taken:
1) Replace auxillary battery. I took out the tiny stock battery and put in the larger one that fills the cage. This size shows as the correct size in many searches and appears to have been installed in many GL modes from the factory.
2) Replace the 1.5 year old battery that tested as having a bad cell. (old and new main are AGM Energizer from costco H8).
3) Remove alternator and found that one of the brushes was not making contact.
4) Replaced the brushes and springs according to the following videos ($13 canadian dollars on amazon):
6) Reinstall alternator
7) tested continuity from negative boost post to alternator housing > all good
8) tested positive alternator post to positive boost post > all good
9) Tested voltage at alternator and it was the same low voltage as the main battery = assume alternator still not putting out proper voltage (or any?). at times the voltage seemed to jump up .25 of a volt and ranged between 11.5 and 11.8v while running on a battery with 12v of charge when the car is off.
All equipment is original except for the new brushes and batteries so far.
Result = same red warning and not charging
Possible issues?
1) maybe the brushes didn't seat properly on the slip rings. its kinda finicky to get it all together with the cap.
2) i cant imagine the solder connections on the brushes are bad, but possible?
3) can an alternator pass all voltmeter tests and still not work?
4) can there be a bad relay or fuse somewhere?
5) open to all other ideas
6) i didn't find any great video about how to bench test voltage output of the alternator with a drill or something because that would have been logical after repair to avoid the extra effort of installing a bad alternator.
i expect a bunch of comments to tell me just to buy a new alternator and this is where i'm basically at... (and wishing i started there). Im just stumped because it should work according to the above videos.
but after all my efforts i would like to have learned something. I also don't want to buy the alternator and find the problem is somewhere else.
Some argue > the alternators are over-engineered and as the brushes are wear items, just deal with the voltage regulator (which can not be easily bench tested). I hoped i found the problem when i saw one slip ring shiny and the other black, as in the videos. Still a mystery of frustration.
Others argue > why replace the voltage regulator when the alternator is next to go or already bad.
many thanks for reading!
matthew
