1990 Volvo 240 Alternator Wiring after reinstalling

[mtberry1]

I replaced my Alternator and consequently, the new alternator had reverse wiring but doesn't seem to be a problem...the problem is i have what seems like an extra ground wire that is Black in color, while my main ground is a large blue wire,large red wire, a small red and a small black...also when i disconnected the old alternator it didn't seem to be attached...So where does it go or should it remain detached>>>???

[jimmy57]

The ground wire may have been replaced. You need to be sure there is a ground wire from case of alternator to the block. The alt mounts on rubber bushing and the tension arm does also. No ground = no output.
The red skinny wire goes to D+/61 blade terminal (Not W terminal if it has one).

[mtberry1]

So there are 2 different grounds???...The main ground from the alternator to the car is there but this Black wire is small and in the same bundle as the little red one....so again where does it go or should i leave it disconnected like the old one...and the car runs normal...the only thing is the oil pressure light stays on ...never did prior to me changing the Alternator.

[5ft24]

it would appear that black wire is for the Oil Pressure sensor, not the alternator