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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Grand Am 🢒 Engine 🢒 Engine Electrical 🢒 Battery Electrical Drain/Parasitic Load Test

Battery Electrical Drain/Parasitic Load Test Diagnostic Procedure

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 theJ 38758 .
  5. Turn the J 38758 to the CLOSED position.
  6. Road test the vehicle while activating all accessories (radio, A/C, 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:
    12. 11.1. Current draw less then 25 millilamps is acceptable. Check the charging system for proper operation. Refer to Starter and Charging, Cell 30 in Electrical Diagnosis.
    11.2. Current draw over 25 millilamps; remove the PCM fuse
    11.3. If the ammeter drops more than 10 milliamps, refer to Battery Electrical Drain/Parasitic Load Test .
    11.4. If the ammeter shows less than 10 millilamps drop, remove the circuit/system fuses one at a time until the current draw returns to a value less than 25 millilamps. this will indicate the circuit/system causing the draw. Refer to the corresponding cell in Electrical Diagnosis.

    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.

Battery Electrical Drain/Parasitic Load Test PCM Draw Test

Before performing the PCM Draw Test ensure that the following conditions are met:

    • The ignition key is out of the ignition.
    • All the doors are closed.
    • The head lights and park lights are Off.
    • The courtesy lights are Off.
    • The battery is fully charged.

Perform the following procedure before starting the PCM Draw Test:

  1. Reconnect the negative battery cable.
  2. Remove the voltage from the PCM memory. Refer to Electrical Diagnosis in Electrical Body and Chassis.
  3. Connect a milliammeter between the terminals.
  4. Read the measurement.

Checks

Action

DEFINITION: PCM current draw should be less than 10 milliamps with no circuits active. The measurement determines the value of the PCM current with all systems off.

    • A measurement above 10  milliamps indicates a possible problem with the PCM.
    • A measurement below 10  milliamps indicates that the PCM is OK.
    • A measurement over 10  milliamps indicates that the problem is not the PCM.
    • A measurement of approximately 0 amps indicates a faulty PCM.

The measurement is over 10  milliamps.

Disconnect the PCM and recheck the current draw as directed.

The measurement is below 10  milliamps

Perform the battery electrical drain check again in order to recheck the current drain.

The measurement is over 10  milliamps
  1. Inspect the ORN wires for a short to ground.
  2. Inspect the components connected to the ORN wires. Refer to Power Distribution in Electrical Diagnosis.

The measurement is approximately 0 amps.

Replace the PCM.