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View Full Version : Charging light dimly lit


rob101
02-12-2007, 04:37 PM
I noticed after fixing my water pump and thermostat. That the charging light was dimly lit on start up and on most trips would completely go out. after a decent drive yesterday, it was more noticeable when i was pulling into my garage. I've been reading bentley and this can mean a number of things from not having water in your battery, alternator problem, regulator problem and a belt problem. Now I don't remember exactly how the m50 belt goes on the engine but i had to refit it to do the water pump. I am worried i may have put it on wrong. does anyone have a decent diagram of how it goes on so that i can eliminate the possibility of a belt problem.
DaveVoorhis
02-12-2007, 04:50 PM
The tensioners pinch the belt, so that the outside of the belt runs on the tensioners, not the inside. If you've put the belt over the top of the upper tensioner, it will work but the alternator may slip.
rob101
02-12-2007, 05:11 PM
The tensioners pinch the belt, so that the outside of the belt runs on the tensioners, not the inside. If you've put the belt over the top of the upper tensioner, it will work but the alternator may slip.
thanks dave, i'll have to check it out when i get home. will sketch a diagram if i am unsure.
rob101
02-17-2007, 06:47 AM
Just did a check with the multimeter.
14.1 V at idle with no accessories
14.0X V at idle with headlights, fog lights, hazards, fan on.
no charging light either this time. I found a hole in my cooling duct for the altenator. Since this problem seems mainly to manifest itself after a decent drive on the highway i figured to patch up the hole since the problem might be heat related. any ideas? I also did a static current draw test. apart from these tests are there any tests i can perform apart from pulling the altenator out?

oh and i checked the belt using a diagram from that BMW service manual that the dude posted up on the M5 boards. seems to be on the right way.
rob101
02-18-2007, 02:04 AM
bump
Boom n Zoom
02-18-2007, 06:17 PM
you've done all the tests that I would run, the next step I would carry out would be to pull the altenator and get it checked out at an Auto Electical place. They can bench run it and diagnose if it is brushes or the diodes.

My suspicion lies with the brushes if the charge light glows though.

Cheers!

BnZ