No battery light - solved

[tsmcg161]

Had to jump her today because she wouldnt start. Got her started and set the time,date. Went to test 09 and she was only reading 11.5 volts. Increase rpm and not nothing changed. Turned her off and turned the key on and I noticed no batt. light. Pulled the cluster back and put in a new bulb and still no light. With key on run posistion I have voltage at my B+ AND D+ on the back of the alternator. I also have voltage at pin 12 at my diag port. I swapped clusters and still no batt light. In line fuse was good by the battery and I even swapped unloader relays. Still no batt light and not charging. I would think if my alternator was completely dead I would at least have a battery light? Stumped!

[shogun]

Next to the battery plus pole is a plug which has 3 wires, 2 for the engine oil level switch and the other one is the exciter wire. This http://bmwe32.masscom.net/sean750/sp...gConnector.jpg
check that, the plugs sometimes break. From there the wire goes with the alternator cable and the 2 oil level wires thru the steel pipe left side of the engine and the exciter wire goes to the alternator.
On my website there are pics of such plug and the wire colors under fixes>>>electrical power>>>Replace charging cable between alternator and distribution post

also a pic with the Bosch plug + number I show there, that plug is not available from BMW as single item.

[tsmcg161]

Key off I have voltage on my B+ cable from the post to the back of the alternator. Key in "run" posistion I have voltage to my D+ wire. I removed the D+ wire from the back of the alternator and grounded the D+ wire and the batt light comes on, so I have a bad ground. Are these alternators internally grounded?

[tsmcg161]

Shogun I found this on one of your links! "If there is battery voltage on D+, temporarily attach the terminal on the end of the D+ wire to chassis ground using a wire with alligator clips at both ends. Then crack the key again. If the light comes on now, it’s likely that the alternator isn’t properly grounded. Check the battery ground cable and the connections on both ends of the alternator ground strap". Im assuming the ground strap in question is the one on the r/h side motor mount?

[tsmcg161]

I think I figured it out. I made room to lay the new alternator on top of the old one. I hooked up my B+ and D+ wires then I used my jumper cables and attached cable to attach point on new alternator and the other end I attached to strut mount bolt. Turned key on and now have battery light. Shogun, it was because of you and the time you spend on this forum and the endless amounts of information you provide all of us is what helped me solve this issue. I am forever grateful for your presence. There have been so many times I wanted to junk this pig but, im fatally attracted to her. Again thank you.

[G46]

for once, i had the issue of no battery light. okay i pulled the cluster, inspect the bulb, its blown, i replaced with a new one, and key on, still no battery light, i was thinking, why there no light eventhough new bulb, since i am an electrical tech, it must be a contact. pull back the cluster out. clean the contact and have a good look on how the bulb sits in the holder and which part makes contact. bam! now i have battery light with key on, started the car. battery light will not go off, another prob! checked with multimeter, 11.5v across the battery. next to check is the carbon brush, then the regulator/rectifier.

[tsmcg161]

New alternator installed. Turn key on and that wonderful battery light illuminates. Ran out of daylight so I was unable to see if new alternator is charging. So now I know the alternator is grounded internally.