Hi all,

History: Purchased 2005 cooper base as a non-runner, overheated (no history), I decided to start with a NOS block and rebuild.

Once completed, the battery charge light was permanently ON, I removed the alternator, it checked out BAD. I replaced with a rebuilt alternator from local alternator/starter rebuild shop along with a new battery.

Now, after starting with new alternator and new battery, same issue the 12v across terminals reduces from 12.6 to 12.1V once idling?.

Verified good:
battery fully charged to 12.6V
New drive belt, correct tension (new tensioner).
Battery posts clean and tight
battery ground wire to chassis
engine ground wire to chassis
continuity engine ground to battery ground
alternator fuse (F39) good
alternator wiring harness connections all good and tight (new signal harness jumper installed)

I don't have a charging system tester, no fault codes with generic scan tool...

Any ideas before I remove the alternator and get it independently checked?

thanks,

Pete.

 

Check first wiring.Here charging system wiring.

 

I just replaced the alternator twice in three days on my R52. The first one lasted 20 minutes and crapped the bed. Got the front end held together with velcro and zippers now. Quality parts are hard to get these days, everything seems to be junk.

 

Regarding the wiring diagram, mine had a Bosch 110Amp 2 wire alternator, so i replaced like for like, noting that the factory loom had a 3 wire harness (includes green/white to 5A fuse) that does not connect as the alternator jumper is only 2 pin, black/yellow & white. When I disconnect the jumper harness from the alternator and key ON the P/S pump runs.

It may well may be down to me not connecting everything correctly, should the large gage RED cable post on the alternator read the same as battery voltage if I connect a voltmeter across it and chassis ground (right engine mount strap)? with key ON and then change once running?

Be nice to figure out a solution before I remove the alternator once more..........

 

0v at alternator post to ground in any condition, guess I will pull this new alternator and have it checked out........

 

can anyone please verify if 0v at alternator and where that cable attaches to the starter motor is correct with engine off ?:

 

'yes' they do piggy back same post to get connection to the battery