I have 1990 240, I replaced the battery, the alternator twice, and all the fuses in the kick panel and the car is still not taking a charge.

I bought both alternators from O Reillys and had them tested-Pass

I hooked up a multimeter to the battery as the car is running and the quickly volts decline

I unhooked all aftermarket accessories the previous owner installed

Cleaned all the grounds

A specialized Volvo mechanic in the area said that only Bosch alternator work on this car as other alternator doesn't generate enough power to activate the exciter circuit.

If any one could help it would be greatly appreciated.

 

when you turn the ignition on, before you start the car, does the alternator light come on?

when you start the car, does the alternator light go out?

without the alternator light circuit working, and performing as described, your alternator won't charge.

is the alternator properly grounded? start the car, and measure the voltage from the engine ground (near the fuel rail where the ground wires go) to the alternator body, if you see more than a small fraction of a volt between them, then the alternator isn't grounded correctly.

to complete these tests, also (with the engine running), measure the voltage from ...
1) battery - terminal to the big red wire on the alternator
2) alternator body to the big red wire
3) engine ground to the big red wire
4) engine ground to the battery (+) terminal

if things are working correctly, all these readings should be very close, and about 1.6V higher than the battery voltage prior to starting the car.

5) big red wire at alternator to battery (+) terminal

that reading should be near 0V.