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Home >> Lexus >> 2021 >> ES 300h Base >> Repair and Diagnosis (Single Page) >> General Information >> Engine Performance >> Parasitic Load Explanation & Test Procedures - General Information >> Testing For Parasitic Load >> Test Procedure Using Test Switch
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Test Procedure Using Test Switch

  1. Turn ignition off. Remove negative battery terminal cable. Install Disconnect Tool (J-38758) test switch male end to negative battery cable. Turn test switch knob to OFF position (current through meter). Install negative battery cable to the female end of test switch.
  2. Turn test switch knob to ON position (current through switch). Road test vehicle with vehicle accessories on (radio, air conditioner, etc). After road test, turn ignition switch to LOCKED position and remove key. Connect ammeter terminals to test switch terminals. See Figure. Select 10-amp scale.
  3. Turn off all electrical accessories. Turn off interior lights, underhood lamp, trunk light, illuminated entry, etc. To avoid damaging ammeter or obtaining a false meter reading, all accessories must be off before turning test switch knob to OFF position.
  4. Turn test switch knob to OFF position to allow current to flow through ammeter. If meter reads wrong polarity, turn test switch to ON position and reverse leads. Turn test switch to OFF position. Observe current reading. If reading is less than 2 amps, turn test switch to ON position to keep electrical circuits powered-up.
  5. Select low amp scale. Switch lead to the correct meter position. Turn test switch to OFF position and compare results to normal current draw. See GENERAL MOTORS PARASITIC LOAD TABLE (MILLIAMPS) . If current draw is unusually high for the vehicle's overall electrical system, remove system fuses one at a time until current draw returns to normal.
  6. Turn test switch to ON position each time door is opened or fuse is removed. Turn switch to OFF position to read current draw value through meter. When the cause of excessive current drain has been located and repaired, remove test switch and reconnect negative battery cable to the negative battery terminal.
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