I have a 93 240, was driving it home at night and it died. I had the battery replaced last week. Took it to autozone and they said the alternator was bad. So I changed it was taking it around the block and it died again like it wasn't keeping charge. Got it back up to autozone was still reading the alternator was bad. The guys there suggested that there could be a fuse somewhere that is blown and not allowing the alternator keeping the battery charged. My question is there a fuse. If not what could be causing this?

 

Does your instrument panel BATTERY symbol come on with the key in POSITION II, then go out as the car is running? If that light does not function your alternator will not charge. Then, another way to get the alternator to start charging is to REV UP the engine over 2,500 RPM, then check to see if the alternator is charging.

 

Yea the light comes on then goes off while running. Once I get it to 2500 RPM how do I check to see if it is charging?

 

Multimeter. Just put the leads on the battery posts with the engine running, the voltage should be about 13.5. Good thing to have, a multimeter. Engine not running, battery should have over 12V to start the car.

 

alternator belts not tighten properly

Sounds as an obvious thing...but I did not tightened the belts enough and the car would do the same as yours...I would just check them to make sure...and check off something simple...

 

Tightened the belts then drove it to work last night, it was fine. Went to leave needed a jump. Got it home, just recelently put a factory radio back in, unplugged that and let it sit over night. Got up this morning and drove it to work no problems and to luch no problems. Could there be someting up with the factory radio? Didnt have any problems before when it was missing one.


sorry on the wait to reply was moving and it got pretty hetic.

 

what lev said about the volt meter.

before starting the car, put the meter in DC Volts, and hook it up across the battery terminals, battery will be between 12 and 12.6V or so. low end of that means battery charge is low. high end of that means battery is fully charged.

now, start the car, and with it running, measure that voltage again. if the alternator and charging circuit are working properly it should be at least 1V or 1.5V higher, like 13.6-14V. if its not, time to start debugging the charging system.

 

Think I may have figured out the culprit. I picked up a factory radio(mine was missing) and installed it. The radio would cut in and out as I let off the throttle. I disconnected the radio monday night and it has started up and ran perfect since then. Could a bad radio drain the battery at night and cause the car to shut off during driving?

 

more likely, something from the radio was connected wrong to the cars wiring.

but, yeah, I suppose its possible the radio drained the battery, that would be pretty easy to test with a digital multimeter...