I have a 3 amp drain on my battery with the ignition key turned off and have traced the drain back to the alternator, however the alternator charges properly. The Mercruiser Mando 55 amp alternator has 5 wires attached.
Of the 5 wires, 2 are heaver gage and are 12v positive and ground. The 3 other wires are labeled "S", "L2", and "EXC". The "S" wire has 12v when the key is on. The "EXC" wire didn't show any voltage. The wire labeled L2 has 12v on it all the time and is the one that is pulling 3 amps from my battery. I can remove this wire from the alternator and the drain is gone. I tried switching the L2 and S wires and started the engine, but the engine would not turn off. somehow the voltage was backfeeding. Does anyone know what kind of voltage readings I should see on these 3 wires?? And what is the L2 wire??
Of the 5 wires, 2 are heaver gage and are 12v positive and ground. The 3 other wires are labeled "S", "L2", and "EXC". The "S" wire has 12v when the key is on. The "EXC" wire didn't show any voltage. The wire labeled L2 has 12v on it all the time and is the one that is pulling 3 amps from my battery. I can remove this wire from the alternator and the drain is gone. I tried switching the L2 and S wires and started the engine, but the engine would not turn off. somehow the voltage was backfeeding. Does anyone know what kind of voltage readings I should see on these 3 wires?? And what is the L2 wire??
