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Home >> Toyota >> 1997 >> Previa LE, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Circuit Tests >> DTC P1520: Stoplight Switch Signal Malfunction >> Diagnosis & Repair
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Diagnosis & Repair

  1. Check stoplights. If stoplights do not function properly, repair as necessary and retest system. If stoplights function properly, go to next step.
  2. Access ECM under driver's seat. Turn ignition on. Backprobing ECM connector, measure voltage between ground and terminal No. 14 (Green/White wire) at ECM E9 connector. With brake pedal depressed, voltage should be 7.5-14.0 volts. With brake pedal released, voltage should be less than 1.5 volt. If voltage is not as specified, go to next step. If voltage is as specified, check wiring harness and connectors. Problem is intermittent.
  3. Check for short in wiring harness between ECM and stoplight switch. Repair wiring as necessary and retest system. If wiring harness is okay, replace ECM. Retest system.
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