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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 67 (Automatic Transmission Diagnosis - A340E, A340F) >> Diagnostic Tests >> DTC P1520: Stop Light Switch Signal Malfunction >> Diagnostic Procedure

Diagnostic Procedure

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  1. Check stop lights. If stop lights do not function properly, repair as necessary and retest system. If stop lights function properly, go to next step.
  2. Turn ignition on. Backprobing appropriate ECM connector, measure voltage between ground and BK or STP terminal. See WIRING DIAGRAMS . 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, problem is intermittent. Check wiring harness and connectors.
  3. Check for short circuit in wiring harness between ECM and stop light switch. Repair as necessary and retest system. If wiring harness is okay, replace ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Retest system.
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