i've been working for the past few weeks on getting my 240 up and running. it needed new engine mounts, some bushings and a series of exhaust and suspension repairs.

somehow in the process the charging system went south. most of my mechanical experience is on motorcycles, where the system is quite different.
i'm hoping someone here can help me troubleshoot. here is where i'm at...

1) the battery can be charged up to a normal (12.6v?) level via a boost or via car charger.
2) the battery is not being charged by the alternator when the car is running.
3) i replaced the alternator (three times now, twice with used units, and now with a newly rebuilt one from a trusted source).
4) the charging warning light is functioning, and comes on when the key is turned.
5) i have tried eliminating the existing wiring harness from the equation by wiring the B+ of the alternator directly to the battery, and grounding the alternator using a wire seperate from the existing ground connection.

is there something obvious i'm missing?...i'm very close to having it towed to the garage for lots of $$$$, which ideally i'd like to save. i also hate to admit defeat, but i need my car back!!!

thanks

 

Check to be sure that the small red wire is connected to its fitting and secured to the spade connector on the alternator. The other end will be connected to behind the instrument cluster. It is the power source that pre-excites the alternator to give voltage. If not pre-excited, the engine needs to get somewhere around 3000-4000 rpm before the alternator will act normally and charge your system. On my car, the spade connector was solid onto the terminal, but the wire had deteriorated so that it fell out of the connector.

 

thanks! i knew that the charging light was part of the circuit, but didn't realize that it could be over rided by rpm.

i had checked all connections to the alternator pretty thoroughly. in the end, i caved and took it to a volvo specialist. apparently the belt adjsuter was not working correctly, so the alternator was putting out a charge, but less of a charge than the battery. he fixed the adjuster and things are working fine. it cost me all of sixty dollars for him to fix, and i had already spent double or triple that troubleshooting this problem, so as much as i hate to admit defeat, it was probably a wise decision.