Shamrock20
Member
I bought a rebuilt Bosch alternator from Autozone (Duralast). It would only charge for about 20 minutes. Autozone said it must be a loose connection or the DME (ICU). After a lor of research I found that the regulator was bad. I replaced it with a NAPA Bosch OEM regulator and the problem was solved. It cost $145. In my opinion this should have been good in a rebuilt alternator but Duarlast does not check to this detail. they just replace the brushes and do a bench test which it would have passed.
If I had it to do over again I would have bought a NAPA Bosch OEM alternator and saved time and money. Duralast alternator was about $200.00 and the regulator was about $145.00 making the entire replacement $345.00 and a lot of extra work. A new Bosch alternator is $299.00 at NAPA.
There was a lot of misinformation posted on the E86 alternator and charging system. There is no IBS on the E86 so don't try to troubleshoot this. The DME does control charging but a quick test recommended by Bosch tech support narrowed down the problem to the regulator.
Bosch tech support told me that if the control from the DME and plugs in to the regulator on the alternator is removed the default is to charge continuously. I removed the plug and the alternator did the same thing it had been doing. It charged for 20 minutes then cutout. It then flipped back and forth from charging for 15 seconds to not charging for about 2 minutes. After I replaced the regulator it charged properly and the battery light is out. Everything is good now.
If I had it to do over again I would have bought a NAPA Bosch OEM alternator and saved time and money. Duralast alternator was about $200.00 and the regulator was about $145.00 making the entire replacement $345.00 and a lot of extra work. A new Bosch alternator is $299.00 at NAPA.
There was a lot of misinformation posted on the E86 alternator and charging system. There is no IBS on the E86 so don't try to troubleshoot this. The DME does control charging but a quick test recommended by Bosch tech support narrowed down the problem to the regulator.
Bosch tech support told me that if the control from the DME and plugs in to the regulator on the alternator is removed the default is to charge continuously. I removed the plug and the alternator did the same thing it had been doing. It charged for 20 minutes then cutout. It then flipped back and forth from charging for 15 seconds to not charging for about 2 minutes. After I replaced the regulator it charged properly and the battery light is out. Everything is good now.