shortimer Posted March 5, 2017 Posted March 5, 2017 My wife's 2001 ES300 has had a slow battery drain that results in a low battery charge and inability for the car to start after several days of not being driven. I first charged the battery to 12.7 volts with a battery charger, I checked the alternator and found charging at 14. 4 volts and took the battery to Pep Boys to conduct a load test and battery condition after 1.5 hour charge. Battery checked out in good condition. I then proceeded to finding what was causing the battery drain. Using a multimeter set on "amps" I removed the ground connector from the battery and hooked one multimeter lead to the battery and the other lead to the disconnected battery ground cable connector. After 3-5 min. with the ground strap disconnected, I took a reading of the battery drain. The multimeter showed a 150 ma current drain. At that point I started pulling fuses to see which would stop the drain. When I pulled the 10a ECU-B fuse the drain immediately dropped to 20ma. The question I have is what devices/circuits receive power through the ECU-B fuse? Second, what further steps can I take to determine what device/circuit fed from this fuse are drawing current with the key off and the car sitting idle?
gbhrps Posted March 6, 2017 Posted March 6, 2017 shortimer, At this stage you need a wiring diagram, something that Lexus does not pass around cheaply. You might try finding a Camry V6 wiring diagram (possibly easier to locate) or go online to a site that allows downloads of sections of Lexus f-Factory Service Manuals for a fee. Here's a link to a site that may have what you need for a $7.50 one month charge: https://www.repairsurge.com/?hop=prowz
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