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?After returning this one and getting a full refund I purchased a remanfactured Bosch unit, installed it and again NO CHARGE and no output @ the alternator posts. I also used a piece of wire and ran a connection from the pos battery and touched it to the small post on the alternator to excite the charging system and no change. I am really frustrated, any ideas or help would be appreciated. Thanks, Bill

 

Those are connected all the time.


Guessing it's not the alternator...
Did you have your original alternator tested? As well as the subsequent alternators?

 

about the only thing in a Kragen's I'd put in my Volvo would be oil and coolant.

 

Do we assume you had your original alternator tested and verified that it was bad????

 

just covering the basics here... when you turn the key on, does the battery light come on? If not that may be an issue. if the bulb doesn't come one--even because it is burnt out--you will not develop a charge.

 

not on all cars.

 

That may be... I seem to recall my '89 740T having the same charging system... But I don't have that car anymore, and I may be confused on that point. Further, I don't have greenbooks for 700/900 series cars, so I can't look it up. Do you know?

 

the alternator light is required to provide the Bosch alternator on all these 2/7/9's with D+ 'kickstart' current. SOME alternators may self excite if they are in a good mood, and you rev the engine above about 2500 rpm, but thats not guaranteed.

 

thinking about it, do remember cars that wouldn't charge until you rev'd it. potentially bad iac system.

I don't have access to wiring diagrams for these cars.

Kind of irrelevant, since where talking about volvo's but I know you can have that light out on other manufactures and the alternator will still charge. Point don't take this info and use it across the board on all cars. Which is why working on cars is so difficult everything is different....

 

IAC (idle air controller) has *NOTHING* to do with the charging system. all the IAC does is help the ECU maintain a constant 700rpm idle (if everything is setup and adjusted correctly, with the IAC unplugged, a warmed up engine should idle at about 500rpm with AC and headlights switched off, the IAC is modulated to let sufficient air past the closed throttle to bring that up to 700rpm, even when the electrical load of the headlights and the mechanical load of the AC are on).

actually, you are somewhat right. the volvo dashboard warning lights have some diodes so that you still get trickle current via some of the other idiot lights if the ALT/BATT bulb is dead but the wiring is still hooked up correctly. if the wire is broken, no charge.

 

 

i am sorry to ask a silly question but i do i post

 

where's the wiring diagram???

 

mine are on a copy protected DVDROM I bought from VCOA, one for all 200 models another for all 900/90 models. theres a 3rd one I dont have for 700 models.