Need some M10 alt help

[Wishno87]

For some reason the power from the alt is not getting to the rest of the car/battery. Any ideas? I don't really have much of any M10 experience. The large red cable just goes to the battery right? Any help would be great, Thanks.

[Wishno87]

Anyone?

[Wishno87]

Lol does anyone have an m10 anymore?

[Eecen]

Might have better luck on 2002faq or the e21 section of bimmerforms?

[Wishno87]

Might have better luck on 2002faq or the e21 section of bimmerforms?

I thought all the '02 guys had S14s and all the E21 guys had M42s?

[Jaxx_]

is it actually charging?

do you have alt light on your dash when running? or in position 2 with the motor off?

give it a rev to 3k and it should start charging even with the exciter circuit malfunctioning. after that it's the alternator itself or cable to the battery.

[Wishno87]

is it actually charging?

do you have alt light on your dash when running? or in position 2 with the motor off?

give it a rev to 3k and it should start charging even with the exciter circuit malfunctioning. after that it's the alternator itself or cable to the battery.

Found out a m10 is supposed to have a completly separate ground wire. Attached a ground wire and life is good.

[Eecen]

So the m10 alt. needs its own ground to charge?

[Wishno87]

So the m10 alt. needs its own ground to charge?

Yup. It Is 100% isolated by rubber bushings.

[Hey_You]

I just had a similar issue with mine. Didn't transfer my worn out ground to the new alternator. Then when I did, it still wasn't right. Ended up being that my m10 318i didn't have the light in the cluster (or it did, but doesn't work) so I had to bypass the ciruit and hardwire my alternator straight to my switched 12v at the ignition switch. Without a constant 12v going to the alternator, it will not charge correctly. I just hardwired my line to the blue wire at the diagnostic port (shared circuit as imput to alternator)

[Jaxx_]

I just had a similar issue with mine. Didn't transfer my worn out ground to the new alternator. Then when I did, it still wasn't right. Ended up being that my m10 318i didn't have the light in the cluster (or it did, but doesn't work) so I had to bypass the ciruit and hardwire my alternator straight to my switched 12v at the ignition switch. Without a constant 12v going to the alternator, it will not charge correctly. I just hardwired my line to the blue wire at the diagnostic port (shared circuit as imput to alternator)

the proper way to do it would be to wire in a resistor inline with the cluster bulb. It is 12V switched for a reason. parasitic drain is something you can prevent from botch jobs like this.

[Hey_You]

Yes, botched is 100% correct, but parasitic drain? None. I'm going directly around the cluster bulb. The bulb gets 12v from the ignition switch (green wire). Then out of the bulb the wire is blue and goes directly to the alternator. Don't get me wrong, I agree with you I should have just fixed it properly, but I had to do something quick. While not "correct" it is 100% effective with the only ugly downside being...the one wire that's not in the loom. I properly did this improper repair. I had my Mitchell1 wiring diagram, voltmeter, test light and quick connect splices (splices because I will fix it correctly, but will wait until I pull my cluster to fix other things while I'm at it). The proper way would be to fix the problem instead of wiring in a resistor. My car was out for 2 months because some yahoo did that before I owned it, and I had to to manually check every sensor/meter/wire before I found it and wired it correctly.
Note: My right forearm/hand is in a cast, so taking stuff apart and back together is a super pain. That's why I did it this way

[Jaxx_]

Yes, botched is 100% correct, but parasitic drain? None. I'm going directly around the cluster bulb. The bulb gets 12v from the ignition switch (green wire). Then out of the bulb the wire is blue and goes directly to the alternator. Don't get me wrong, I agree with you I should have just fixed it properly, but I had to do something quick. While not "correct" it is 100% effective with the only ugly downside being...the one wire that's not in the loom. I properly did this improper repair. I had my Mitchell1 wiring diagram, voltmeter, test light and quick connect splices (splices because I will fix it correctly, but will wait until I pull my cluster to fix other things while I'm at it). The proper way would be to fix the problem instead of wiring in a resistor. My car was out for 2 months because some yahoo did that before I owned it, and I had to to manually check every sensor/meter/wire before I found it and wired it correctly.
Note: My right forearm/hand is in a cast, so taking stuff apart and back together is a super pain. That's why I did it this way

it doesn't make sense to me that there would be no parasitic drain... I'll take your word for it though.

[Hey_You]

It's because the green wire is 12v switched at the ignition. The light is just inline. I only have 12v at the wire I tapped into when the key is "on". Just as your alternator would only have 12v going into it when the ignition is "on". Essentially what I did was cut out the indicator that I'm not charging and put a wire there instead. I won't know immediately when my alternator goes out, but it's new so hopefully I won't have to think about it for awhile.

[Jaxx_]

It's because the green wire is 12v switched at the ignition. The light is just inline. I only have 12v at the wire I tapped into when the key is "on". Just as your alternator would only have 12v going into it when the ignition is "on". Essentially what I did was cut out the indicator that I'm not charging and put a wire there instead. I won't know immediately when my alternator goes out, but it's new so hopefully I won't have to think about it for awhile.

oh true. okay I was thinking you just went straight from the battery to D+. Carry on.