exx1976

Ok.. Already checked the usual culprits - all the wires are tight, none are melted (this time), everything is as it should be. HOWEVER, when I'm idling (stop sign or light for instance) under load (heat on (cold with the top down), stereo on (two subs)), I get a "check charging system" message and the battery light comes on. Gauge doesn't move. It goes away as soon as I hit ~1200 RPM. I tried grabbing DTCs, and there are none.

Anyone? How can I check for a bad alternator? I have a DVOM, what should the voltage be when the car is running? I'm guessing I just check it across the battery terminals? I'd like to narrow it down for sure so I don't waste a trip to the dealership, only to be charged for something stupid..

TIA for all the help!

J2L06GT

You should read about 13.8v when
system is working correctly.

moosestang

13.8 - 14.1 volts for me.

exx1976

After calling the local dealership and not being able to get a service guy on the phone on three separate attempts, I have an appointment for next Thursday at the Saleen dealer over an hour away. I told them it's a GT with a Saleen blower, it was installed at a SpeedLab, they said no problem, as long as it's a factory alternator to bring it right down and they'd take care of it.

Sounds good to me.

charliebrown266

the voltage should be about 14.1 volts. should also check to see how many amps it can put out,should be over a 100amp under load,that you can not check with a volt meter, are you using under drive pullys? Are you using a caps for the subs? If not depending on your subs you can be drawing over 50 amps from the alternator at idle and the blower motor at least another 15 amps.witch is big load at idle. combined with all the other elec being used to run the car.