Which Battery Cable Do You Remove To Test Alternator. The first test can be done at your garage. Once youve done this let it run for about five to 10 minutes then disconnect the jumper cables and try to start it up on its own.
Remove the drive belt. Disconnect the positive terminal of the car battery while it is still running. Disconnecting a battery cable to check the alternator is not a good idea.
If you disconnect the battery and the car conks out you dont know if it conked out due to insufficient alternator current or whether the resulting transients caused your ECU the cars computer which controls fuel mixture timing and much more to spit out bad data shutting down the car.
Alternator test with a voltmeter If youre tempted to test an alternator by disconnecting the negative battery cable dont do it. You need to start the car by keeping the hood open. It can destroy your ECM computer alternator and various sensors. To do a quick check on an alternator I was told that you could start the car and then remove the negative battery cable.
