Parasitic Load Testing

- J 38758 Parasitic Draw Test Switch Tool
- J 39200 Digital Multimeter (DMM)

NOTE: The parasitic draw test switch should never be turned to the OFF position with the engine running. Damage could occur to the attached ammeter or the vehicle electrical system.

1. Disconnect the negative battery cable.
2. Connect the J 38758 male end to the negative battery terminal.
3. Turn the test switch knob to the OFF position.
4. Connect the negative battery cable to the J 38758 female end.
5. Turn the J 38758 to ON.
6. Road test the vehicle with all of the accessories on.
7. Turn the ignition switch to LOCK.
8. Remove the ignition key.
9. Use a DMM set to amps scale to measure current.
10. Connect the DMM to the test switch terminals with alligator clips.
11. Turn the J 38758 to OFF.
12. Wait 10 minutes.
13. Check the current reading:
- A zero reading indicates a problem with the DMM, the scale being used or a connection.
- A reading below 25 mA is acceptable.
- If the reading is above specification, perform the following:
13.1. Remove the system fuses one at a time until current draw returns to a value less than or equal to the specifications.
13.2. Perform steps 11 and 12 above each time a fuse is removed.
- A reading above 100 mA may suggest the following:
- Grounded wires
- Sticking relays
- A light is on.
Refer to Diagnostic Aids in Diagrams in order to make necessary repairs.
14. When the cause of the current draw has been located and repaired, perform the following:
14.1. Repeat steps 11 and 12 above in order to verify the repair.
14.2. Turn the J 38758 to OFF.

NOTE: Refer to Fastener Notice in Cautions and Notices.

14.3. Remove the J38758.
14.4. Connect the negative battery cable.

Tighten
Tighten the negative battery cable to 15 N.m (11 lb ft).