2008 Lexus RX 350
Looking for help in troubleshooting a problem with battery draining after 2-3 days if car is not started. New battery and charging system checks OK. Have had to replace the battery 3 times in last 2 years, and twice in last 5 months. Car is being driven infrequently these days, 20-25 miles/month. Had a shop check the charging system - said it was OK.
Troubleshooting completed
Used ammeter between negative battery cable and negative terminal to measure current. With all fuses in, current starts at ~680ma, drops to ~320ma after 1 minute, drops again to ~110ma after 5 minutes, and finally drops to ~80 ma. The current stays at 80ma most of the time, and occasionally drops to ~60ma.
Started pulling fuses one at a time. Only 2 fuses affect the current. With both of these pulled, current goes to zero.
ECU-B, Fuse 24 (7.5 amp) under hood. Has several circuits - power window, multiplex communication system, gauge and meters, instrument cluster lights, air conditioning system, garage door opener, illuminated entry system, power back door, driving position memory system, navigation system display, moon roof, tilt and telescopic steering, power seats, outside rear view mirror, windshield wipers.
When ECU-B is pulled, current reduces to ~60ma
ECU-ACC, Fuse 28 (7.5 amp) under driver side dash. Circuits on this fuse - navigation system display, power rear view mirror control, shift lock control system, multiplex communication system.
With ECU-B and ECU-ACC pulled, current goes to zero, so ~60ma on this fuse.
I exercised all switches and checked to make sure that lights, etc were off when the car is powered down - all looks OK.
1. What should be the normal current after car systems power down? Is 80ma normal?
2. Any ideas on what components are most suspect to cause problem?
Thanks for any help on this!
