Volvo 240 1990 alternator problems?

Cassman500 · Post by **Cassman500** » 12 Apr 2010, 14:21

I'll try to be as descriptive as possible so i can make get idea of whats going on because i have no clue at this point. Several months ago my car died, the lights, radio, etc. slowly dimmed and finally died. i jumped it with another vehicle and it ran for about 2 minutes and died again. So at this point i realized it was the alternator. i went to a local junk yard got a used one and put it in. This worked for about two weeks then the same thing happened. however i could jump it and it would run
so i thought it was a bad battery. i bought a new battery and it things were fine for a week then again the car would die. so again i went back to the alternator. i got another used one that i knew for sure was working yet it still will not charge the battery. i checked the volts of the battery before i started it and it read 12.5 as soon as i started it the volts went down to 12 and began to drop so i knew it wasn't getting charged. So now my current thought is that possible there is problem in the wiring connection between the alternator and the battery so ive began un snaking it through. I'm curious if there is something obvious i am missing or a step i should take before i start messing with the wiring. my buddy is an electrian and would be able to repair the wiring for me if that is the case. Any help what so ever would be greatly appreciated i've been dealing with this for around two months now and i just want to get her back on the road ha. Thanks again, Andrew

Post by **billofdurham** » 12 Apr 2010, 15:35

Is the alternator earthed (grounded)? Some have a separate earth wire as they are mounted in rubber bushings.

If that isn't the problem the attached is a check list for the alternator:

240 1990 alternator test.pdf: (716.42 KiB) Downloaded 1286 times

Bill.

Cassman500 · Post by **Cassman500** » 12 Apr 2010, 16:41

There is a ground wire between the back of the alternator towards the bottom and the mounting bracket.

Cassman500 · Post by **Cassman500** » 19 Apr 2010, 16:03

I'm wondering what the black wire that connects to a port on the engine block is for? a second ground of some sort? the other two connect to the back of the alternator but im not sure what the black one does

mtberry1 · Post by **mtberry1** » 08 Dec 2013, 19:57

Cassman500 wrote:I'm wondering what the black wire that connects to a port on the engine block is for? a second ground of some sort? the other two connect to the back of the alternator but im not sure what the black one does

Yes...what is the black wire for???

docmjh1 · Post by **docmjh1** » 11 Feb 2014, 10:48

might be the wire for the oil pressure sensor

5ft24 · Post by **5ft24** » 04 Apr 2014, 13:56

should have the fat wire for the charge out, 2 wires coming out of a harness for B+ and Charge light, and the ground wire. Ground on Mine goes to a bolt on the intake manifold.