Drain Test

WARNING: DO NOT ATTEMPT THIS TEST ON A LEAD-ACID BATTERY THAT HAS RECENTLY BEEN RECHARGED.

CAUTION: Do not crank the engine or operate accessories that draw more than 10 A.

NOTE:
^ You must wait approximately 50 minutes after the doors have been opened before performing this test.
^ Many modules draw 10 mA or more continuously for their keep alive Random Access Memory (RAM).
^ Use an in-line ammeter between the battery positive or negative post and its respective cable.
^ Do not start the vehicle with a clip-on cable.

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 with this procedure:






1. Insert the test leads in the input terminals.
2. Turn the 73 Digital Multimeter switch to mA/A dc.
3. Disconnect the battery ground cable and touch the probes.
4. Isolate the circuit causing the current drain by removing one fuse after another while reading the display.
5. The current reading will drop when the fuse on the bad circuit is pulled.
6. Reinstall the fuse and test components (including connectors) of that circuit to find defective component(s).

Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp, or luggage compartment lamp staying on continually. Other component failures or wiring shorts may be located by selectively pulling fuses to pinpoint the location of the current drain. When the current drain is found, the meter reading will fall to an acceptable level. If the short is still not located after checking all the fuses, the drain may be due to the generator.