Diagnosing Class 2 Serial Data Line

1. Pull the COMFORT, IGN0 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 (BCM) "awake." Do not replace the BCM until the whole test is complete. If the current draw does not go away, Refer to the traditional excessive current draw in this procedure.
2. Reinstall the COMFORT fuse. This will "wake up" the Class 2 serial data line.
3. Wait 20 minutes.
4. When the BCM goes back to sleep, monitor the current draw using a DMM. 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 a DMM. If the excessive current draw is removed, then the parasitic drain can be isolated to the RFA module and its related circuits.
7. Disconnect the CD changer, if equipped.
8. Monitor the current draw using a DMM. If the excessive current draw is removed, then the parasitic drain can be isolated to the CD changer and its related circuits.
9. Disconnect the ACM.
10. Wait 20 minutes.
11. When the BCM goes back to sleep, monitor the current draw using a DMM. If the current draw is excessive, the cause of the parasitic drain can be isolated to the BCM and its related circuits.
12. Do not replace the BCM until all of the components powered by the controlled power relay have been diagnosed.
13. Reinstall the IGN0 BODY fuse (equipped with a climate control panel CCP).
14. Monitor the current draw using a DMM. If the current draw is excessive, the cause of the parasitic drain can be isolated to a component that receives power from the IGN0 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 a DMM. 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 the parasitic load test switch and connect the negative battery cable to the negative battery terminal.

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

NOTE: Refer to Fastener Notice in Cautions and Notices.