Drain Testing Procedures

NOTE: A voltmeter is sometimes used for this test but it will react to a very small normal drain caused by always-on electronic systems such as starter interlock, anti-theft alarm and illuminated entry, which cause no concern. The test lamp shows only drains which are large enough to cause a concern.

Check for current drains on the battery in excess of 50 milliamps with all the electrical accessories off and the vehicle at rest. Current drains can be tested one of three ways:
1. Connect a 12-volt test lamp in series with battery positive terminal. If lamp glows, then a drain exists.
2. Use a clamp-on current probe to the battery positive or negative cable. Make sure that the probe is properly calibrated to prevent false readings.
3. Use an in-line ammeter between the battery positive or negative post and its respective cable.