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Parasitic Draw Test

Check for current drains on the battery in excess of 50 milliamps (0.050 amp) with all the electrical accessories off and the vehicle at rest. Current drains can be tested with the following procedure:

  1. Make sure the junction box/fuse panels are accessible without turning on interior and underhood lights.
  2. Drive the vehicle at least 5 minutes and over 30 MPH to turn on and exercise vehicle systems.
  3. Allow the vehicle to sit with the key off for at least 40 minutes to allow modules to time out/power down.
  4. Connect a fused jumper wire between the negative battery cable and the negative battery post to prevent modules from resetting and to catch capacitive drains.
  5. Disconnect the negative battery cable from the post without breaking the connection of the jumper wire.
    6. NOTE: It is very important that continuity is not broken between the battery and the negative battery cable when connecting the meter. If this happens, the entire procedure must be repeated.
  6. Connect the tester between negative battery cable and the post. The meter must be capable of reading milliamps and should have a 10 amp 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.
  7. Remove the jumper wire.
    8. NOTE: Amperage draw will vary from vehicle to vehicle depending on the equipment package. Compare to a comparable vehicle for reference. A periodic pulsing of up to 80 mA (0.080 amp) is caused by the Integrated Control Panel (ICP) and should be considered normal. However, no production vehicle should have more than a 50 mA (0.050 amp) draw.
  8. If the draw is found to be excessive, pull fuses from the battery/central junction box one at a time and note the current drop. Do not reinstall the fuses until you are finished testing.
  9. Check the wiring schematic in the wiring diagram for any circuits that run from the battery without passing through the battery/central junction box. Disconnect these circuits if the draw is still excessive.

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