Parasitic Draw Test

Parasitic Draw Test:

Tools Needed:
J 38758 Parasitic Draw Test Switch
J 39200 Fluke 87 Digital Multi-Meter

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. Remove battery cable from battery negative terminal.
2. Install the parasitic draw test switch male end to negative battery terminal.
Tighten
^ J 38758 to 15 N.m (11 lb. ft.).
3. Turn test switch knob to the "OFF" position.
4. Install negative battery cable to female end of the test switch tool.
Tighten
^ Negative battery cable to 15 N.m (11 lb.. ft.).
5. Turn the test switch knob to the "ON" position.
6. Open the trunk in order to access the trunk compartment fuse block.
7. Turn ignition switch to the "Lock" position and remove ignition key.
8. Connect J 39200 terminals on test switch tool.
9. Turn test switch tool knob to the "OFF" position to allow current to flow through the ammeter.
10. After approx. 20 minutes check current reading. If current draw is above 30 milliamps the load can either be that a module on the Class 2 serial data line is not going to "sleep" or that the load is related to a traditional excessive current draw if lumbar seat switch stuck on.

Diagnosing Class 2 serial data line.
1. Pull the COMFORT, IGNO BODY, and BATT fuse(s). If the draw goes away the most likely cause is that a module on the Class 2 serial data line is keeping the Body Control Module (PZM) "awake." Do not replace the PZM until whole the test has been completed. If the current draw does not go away, refer to traditional excessive current draw in the procedure.
2. Reinstall the COMFORT fuse. This will "wake up the Class 2 serial data line.
3. Wait approx. 20 minutes.
4. When the PZM goes back to sleep, monitor the current draw using J 39200. If the current draw is excessive, the cause of the parasitic drain can be isolated to a component that receives power from the COMFORT fuse or a component that is powered by the Controlled Power Relay. If no change is noted in the current draw, proceed to the next step.
5. Disconnect the RFA Module.
6. Monitor the current draw using J 39200, if the excessive current draw is removed, then the parasitic draw can be isolated to the RFA Module and its related circuits.
7. Disconnect the CD Changer, if equipped.
8. Monitor the current draw using J 39200, if the excessive current draw is removed, then the parasitic draw can be isolated to the CD Changer and its related circuits.
9. Disconnect the ACM.
10. Wait approx. 20 minutes.
11. When the PZM goes back to sleep, monitor the current draw using J 39200. If the current draw is excessive, the cause of the parasitic drain can be isolated to the ACM and its related circuits.
12. Do not replace the PZM until all of the components powered by the Controlled Power Relay have been diagnosed.
13. Reinstall the IGNO BODY fuse (equipped with a Climate Control Panel CCP).
14. Monitor the current draw using J 39200. If the current draw is excessive, the cause of the parasitic drain can be isolated to a component that receives power from the IGNO BODY fuse. If no change is noted in the current draw, proceed to the next step.
15. Reinstall the BATT fuse.
16. Monitor the current draw using J 39200. If the current draw is excessive, the cause of the parasitic drain can be isolated to a component that receives power from the BATT fuse. If no change is noted in the current draw, proceed to the next step.
17. When cause of excessive current draw has been located and repaired, remove current drain test tool and connect negative battery cable to negative battery terminal.
Tighten
^ Negative battery cable to 15 N.m (11 lb. ft.).

Traditional Excessive Current Draw
1. When current draw is above 30 milliamps, remove system fuses one fuse at a time until the current draw returns to a value less than or equal to 30 milliamps.
2. Repeat parasitic current drain procedure after any repair has been completed.
3. When cause of excessive current draw has been located and repaired, remove current drain test tool and connect negative battery cable to negative battery terminal.
Tighten
^ Negative battery cable to 15 N.m (11 lb. ft.).