battery light

[mikemrq]

Have a 96 Contour 4cyl. The battery light comes on and off, usually goes off on low rpm but as the rpm goes up the light comes on. I checked the belt and it looks good and tight. I read another post about this, that said to cut the red wire from the connector and run it to the large wire on the alternator. If I did this would the light go out if it was a wiring problem and come on if it actually is the alternator?

[Davescort97]

I wouldn't do that. Take a volt/ohmeter tester and check the battery voltage while the car is running. Should be 13.8 to 14.3 volts. With the engine off it should be close to 12.8 volts. If the voltage isn't within this range while the engine is running the alternator is probably defective. If the battery voltage is less than 12 volts with the engine off, it probably needs to be replaced. An alternator with the brushes worn will not have enough spring pressure to hold them against the commutator at higher engine speeds. Another reason for the light coming on could be that one or more of the wires going into the alternator are loose.

[mikemrq]

tested the battery with the engine turned off, it showed 12.6 When I started the car it showed 14.7 but when the battery light came on when at idel it showed 11.8

[Davescort97]

I think the battery is all right. I would replace the alternator with a rebuilt. Either the brushes are worn out or the internal voltage regulator is bad.

[mikemrq]

Took it to Advanced auto to have it checked. They said the battery is good but the alternator is putting out 9 amps.

[Davescort97]

I think the amperage is supposed to be 75 amps. The brushes were probably worn out too. I hope you don't have anymore problems with it.