Battery - Drain Tests

BATTERY - DRAIN TESTS

WARNING: Do not attempt to service, charge, recharge or jump start a battery unless the following information has been read and understood. Failure to follow this instruction may result in serious personal injury.

CAUTION: To prevent damage to the meter, do not crank the engine or operate accessories that draw more than 10A.

NOTE:
- No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.
- Many electronic modules draw 10 mA (0.010 amp) or more continuously.
- Use an in-line ammeter between the negative battery post and its respective cable.
- Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp or an interior lamp staying on continually. Other component failures or wiring shorts are 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 drain is still not located after checking all of the fuses, it is due to the generator.
- To accurately test the drain on a battery, an in-line ammeter must be used. Use of a test lamp or voltmeter is not an accurate method due to the number of electronic modules.

Check for current drains on the battery in excess of 50 mA (0.050 amp) with all of the electrical accessories off and the vehicle at rest for at least 40 minutes. Current drains can be tested with the following procedure:
1. Make sure the battery junction box (BJB) and the smart junction box (SJB) are accessible without turning on the interior lights.
2. Drive the vehicle for at least 5 minutes and over 48 km/h (30 mph) to turn on and activate the vehicle systems.
3. Allow the vehicle to sit with the key OFF for at least 40 minutes to allow the modules to time out/power down.
4. Connect a fused (30A) jumper wire between the negative battery cable and the negative battery post to prevent the modules from resetting and to catch capacitive drains.
5. Disconnect the negative battery cable from the negative battery post without breaking the connection of the jumper wire.

6. NOTE: It is very important that continuity is not broken between the negative battery cable and the negative battery post when connecting the meter. If this happens, the entire procedure must be repeated.

Connect the battery tester between the negative battery cable and the post. The meter must be capable of reading milliamperes and should have a 10A capability.

7. NOTE:
- If the meter settings need to be switched or the test leads need to be moved to another jack, the jumper wire must be reinstalled to avoid breaking continuity.
- Amperage draw varies from vehicle to vehicle depending on the equipment package. Compare to a similar vehicle for reference.
- No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.

Remove the jumper wire.

8. Note the amperage draw. Draw varies from vehicle to vehicle depending on the equipment package. Compare to a similar vehicle for reference. No factory-equipped vehicle should have more than a 50 mA draw (0.050 amp).
9. If the draw is found to be excessive, remove the fuses from the SJB one at a time and note the current drop. Do not reinstall the fuses until you are finished testing. To correctly isolate each of the circuits, all of the fuses may need to be removed. After removal of all of the fuses, install a fuse, note the amperage draw, then remove the fuse and install the next fuse until each circuit is tested. When the current level drops to an acceptable level after removing a fuse, the circuit containing the excessive draw has been located.
10. If the current draw is still excessive, remove the fuses from the BJB one at a time and note the current drop. Do not reinstall the fuses until you have finished testing. To correctly isolate each of the circuits, all of the fuses may need to be removed. After removal of all of the fuses, install a fuse, note the amperage draw, then remove the fuse and install the next fuse until each circuit is tested. When the current level drops to an acceptable level after removing a fuse, the circuit containing the excessive draw has been located.
11. Check the wiring schematic in the wiring diagram for any circuits that run from the battery without passing through the junction boxes. If the current draw is still excessive, disconnect these circuits until the draw is found. Also disconnect the generator electrical connections if the draw cannot be located. The generator may be internally shorted, causing the current drain.