Parasitic Load Testing

TOOLS REQUIRED
J 38758 Current Draw Test Switch

1. Remove the Battery cable from the negative battery terminal.
2. Install the current drain test tool, male end, to the negative battery terminal.
3. Turn the J 38758 to the OPEN position.
4. Install the negative battery cable to the female end of the J 38758.
5. Turn the J 38758 to the CLOSED position.
6. Road test the vehicle while activating all accessories (radio, NC, etc.).
7. Turn the ignition switch to the locked position and remove the ignition key.
8. Set the ammeter to the 10 amp scale and connect to the terminal on the J 38758
9. Turn the J 38758 in order to the OPEN position to allow current to flow thorough the ammeter.
10. Wait at least 60 seconds, proceed to check the current reading. If the current reading is at or below two amps, close the J 38758 (to maintain continuity in the electrical system) and switch down to the two amp scale for a more accurate reading when the J 38758 is reopened.
11. Proceed as follows:
11.1. Current draw less then 25 milliamps is acceptable. Check the charging system for proper operation.
11.2. Current draw over 25 milliamps; remove the PCM fuse
11.3. If the ammeter drops more than 10 milliamps, refer to Battery (Parasitic) Load Test (PCM Draw Test). Battery Electrical Drain/Parasitic Load Test
11.4. If the ammeter shows less than 10 milliamps drop, remove the circuit/system fuses one at a time until the current draw returns to a value less than 25 milliamps. This will indicate the circuit/system causing the draw.

IMPORTANT: Repeat parasitic current drain procedure after any repair has been completed.

12. When cause of excessive current draw has been located and repaired, remove current drain test tool and reconnect the negative battery cable. Reset the clock, radio, etc.