Question about 2002 Lexus RX 300

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Battery keeps draining when car sits for several days.

Battery discharges when vehicle sits idle for several days. I have replaced the battery, alternator, dome light, and door switch all in the last 4 months. The car is still discharging the battery. There is a low voltage drain somewhere in the vehicle, but where? It appears this is a common problem in these vehicles as I have read about other vehicle with the same issue. HELP PLEASE!!!

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  • Lexus Master
  • 5,252 Answers

Try this to see if you can find the drain: Wait until the car has been off for a half hour, so computer is in sleep mode. Open hood and remove underhood light bulb. Take off negative cable from battery and hook up a test light between cable end and battery post. If you have a drain, bulb should be brightly lit. Start removing fuses one by one until light goes off. When a fuse is pulled that turns light off, that is the problem circuit. Check everything on that circuit to find what is staying on.

Posted on Jan 23, 2013

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Posted on Jan 02, 2017

  • 7 Answers

SOURCE: battery drains overnight

some time the radio will put a drain on the batt. if it has a short. pull the radio fuse, charge the batt. and let it sit over night to see if it drains.

Posted on Jan 02, 2009

  • 3 Answers

SOURCE: I suspect a weak battery, but how do I know it's not a bad ALT?

when your car is running disconnect the positive cord from the battery. if the car stays on, than it is your alternator, if not its your battery. also if the car stays on, the head lights go dim if the alternator is malfunctioning

Posted on Mar 18, 2009

  • 436 Answers

SOURCE: front dome light always on and drains battery

switches go bad in the doors. Easy to replace, fairly cheap.

Posted on Nov 17, 2009

  • 166 Answers

SOURCE: 1990 lexus ls 400 security system went off now

Okay you may want to check to see if the sensor on door lock cylinder hasn't fallen off from the lock itself. Pull of the door panels and check the wires at the door lock cylinder. Hope this helps.

Posted on Mar 25, 2010

tunde007
  • 2382 Answers

SOURCE: hi.my son (college student/part time

Hi, causes of excessive current drain from a car battery include things like lights that remain on (trunk and hood lights, interior lights, brake lights, etc.) and also relays that may be stuck on, or modules that are not going to sleep or powering down. A fuel pump relay that sticks on may keep the fuel pump running after the engine is shut off. A switch or relay that powers a rear window defogger can stick on, pulling current from the battery after the ignition is off. An electronic suspension module, ABS module or keyless entry module may remain active long after it should have powered down.An accessory such as a DVD player, game console or cell phone charger left plugged into a rear seat power receptacle may be pulling power from the battery. So before you spend a lot of time trying to figure out where the amps are disappearing, check all of the vehicle's power receptacles to see if something is plugged in that may be using power.

FINDING THE CAUSE OF THE CURRENT DRAIN


If the key-off current reading is above specifications (typically, more than 50 mA one hour after the vehicle has been shut off), the current drain is too high. It's time to start pulling fuses and relays to find the fault. Refer to your vehicle owner's manual or a wiring diagram to identify the fuses and relays. Then pull the fuses and relays one at a time until the current reading drops. Avoid pulling the fuses for the PCM or other KAM-sensitive modules until you have checked all of the other circuits.
Once you've found the circuit that is causing the excessive current drain, check the relay, switch, module or other components in the circuit and replace as needed.
Sometimes a bad alternator diode can cause a car battery to run down. A good diode should only pass current in one direction. If it leaks current in the opposite direction, it may keep the charging circuit on when the engine is not running, causing the battery to run down.

Posted on Oct 06, 2010

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