Transmission Control System

P1520 - Stop Light Switch Signal Malfunction

CIRCUIT DESCRIPTION

DTC Detection Condition:

The purpose of this circuit is to prevent the engine from stalling while driving in lock-up condition, when brakes are suddenly applied.
When the brake pedal is depressed, this switch sends a signals to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.

Wiring Diagram:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the TOYOTA hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

Steps 1 - 2:

Step 3:

TOYOTA hand-held tester:

Steps 1 - 2:

Step 3:

OBD II scan tool (excluding TOYOTA hand-held tester):