Hi, I have a 1990 760 turbo, the problem is that it stopped charging so I went to my local kragen and got a rebuilt alternator and installed it, it went to 14 volts on the dash gauge for about 5 seconds and then dropped to 11.5 and stayed there, so I returned it and got a free replacement. When I installed this one I was watching the amp gauge as I tried it for the first time and this one did not even show any charging at all, I put a multimeter on it and it showed no charge(same as battery voltage). My question is:could this one be a second DOA part or is there something in the charging circuit that could blow the alternator immediately upon turning the key, all of the wiring looks tight and correct with no damage anywhere. I have ordered a new voltage regulator and I will install it and see if this fixes it but I would like to know if I should look for something that might kill this before I turn the key. Please let me know any info that might help. Thanks, Bill

 

What did/does your old alternator show? I never get the Kragen and such rebuilts, I first always change the brushes and it almost always works unless the thing has half a million miles... Do your warning lights work, the BAT light especially? What happens when you rev the car? Make sure the terminals are tight and clean!

 

Hi Lev, the old one showed no charge at the amp gauge, I should recieve a new regulator today that I ordered and I will post the results, I was going to return the second new alternator but I thought I would try a new regulator/ brushes first. I should have expected problems with the "lifetime Kragen" unit but I took a chance. Do you know of anything in the circuit that could kill an alternator immediately upon installation?, all connections are tight and clean. I hope this will do the trick, if not I will deal with the "experts" @ Kragen one more time. Thanks for your reply, Bill

 

I am skeptical of 'amp gauge' readings, are you using a multimeter? I don't know what would kill an alternator just like that.
I am more intersted in the alternator that came out of your car...
Again, Are your warning lights turning ON? The BAT light?

 

Hi Lev, Yes I am using a multimeter and it showed 0 volts at the rear of the alternator
( other than battery voltage), I did disconnect the leads from the rear and checked it and again 0 volts. And the battery light does NOT come on . I checked the larger cable on the rear of the unit and it does have battery voltage and the other smaller line has 0 volts ( both readings with the key off). Should the smaller wire have any voltage with the key off and disconnected from the alternator?I believe it is a feed to the inst. cluster,a/c,srs, and ECC control, do you know if this is correct?, I checked all of the fuses and none are bad. I am going to exchange the alternator ONE MORE TIME but this time I will bring the pully and have them check it before I bring it home, Thanks again for your help, Bill.

 

Why are you disconnecting the leads? Connect everything the way it should be and then measure it, just across the battery terminals--that's how you read it! The BAT light should be ON as the key is in position II, then shut off as the car starts. This "excites" the alternator into charging mode. Another way is to rev up the motor to over 2,500RPM, and this will also get the alternator going.

You may want to post this in the 2/740/940 section. Your charging system is identical to the 740 and there you'll get a lot more responses.