R50/53 Battery? Alternator?
#1
Battery? Alternator?
My ‘05 MCS has been the source of ongoing frustration and now it seems to be my electrical system.
Last week I diagnosed a faulty alternator. The battery was load tested and passed. When running the voltage of the battery did not change, which lead me to think it was the alternator. I purchased a rebuilt Bosch unit and installed it myself, taking extra care the ensure that the belt was on correctly during resinstall. I fired the car up and my multimeter showed a healthy voltage.
Yesterday I took the car out and it ran great; no error codes or warning lights.
This morning I started the car and let it run for a few minutes with the heat on (it was a cold morning) and when getting in to leave I was met with the dreaded battery warning light. I pulled out my multimeter and the battery voltage showed 11.2. I then turned the car off and checked again, this time it
showed around 12. I turned the car back on and removed the negative lead and the car turned itself off.
Seems like the alternator, but it was working great 16 hours prior.
I also checked the grounding straps and did a visual inspection of the wiring that I could see. Nothing seemed out of place. I also replaced the #39 fuse in the hope that it might be a blown fuse.
Lastly, I just pulled the following codes from my car:-5E16 CAN connection to instrument cluster
-5E1F vehicle identification number different
-0B safety battery terminal (Car has never been in an accident)
-00 internal fault in control unit:internal voltage (x14)
-03 function switch (relating to sunroof)
I am at a loss. Anyone have any suggestions. I was thinking about just buying a new battery to see if that helps as my current battery is around 4 years old.
Any help would be appreciated!
Last week I diagnosed a faulty alternator. The battery was load tested and passed. When running the voltage of the battery did not change, which lead me to think it was the alternator. I purchased a rebuilt Bosch unit and installed it myself, taking extra care the ensure that the belt was on correctly during resinstall. I fired the car up and my multimeter showed a healthy voltage.
Yesterday I took the car out and it ran great; no error codes or warning lights.
This morning I started the car and let it run for a few minutes with the heat on (it was a cold morning) and when getting in to leave I was met with the dreaded battery warning light. I pulled out my multimeter and the battery voltage showed 11.2. I then turned the car off and checked again, this time it
showed around 12. I turned the car back on and removed the negative lead and the car turned itself off.
Seems like the alternator, but it was working great 16 hours prior.
I also checked the grounding straps and did a visual inspection of the wiring that I could see. Nothing seemed out of place. I also replaced the #39 fuse in the hope that it might be a blown fuse.
Lastly, I just pulled the following codes from my car:-5E16 CAN connection to instrument cluster
-5E1F vehicle identification number different
-0B safety battery terminal (Car has never been in an accident)
-00 internal fault in control unit:internal voltage (x14)
-03 function switch (relating to sunroof)
I am at a loss. Anyone have any suggestions. I was thinking about just buying a new battery to see if that helps as my current battery is around 4 years old.
Any help would be appreciated!
#2
#4
With the engine running, check the voltage at the alternator output, make sure that connection is tight.
Also check for continuity between the alternator output and the + cable at the battery.
Lastly check for continuity between the alternator body (ground) and chassis ground.
Also check for continuity between the alternator output and the + cable at the battery.
Lastly check for continuity between the alternator body (ground) and chassis ground.
The following users liked this post:
ssoliman (10-30-2021)
#5
It seems that the rebuilt alternator is no good. I’ve returned it and will look to buy a new OEM replacement.
The following users liked this post:
ssoliman (10-30-2021)
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