Transmission Control System

P1520 - Stop Light Switch Signal Malfunction

CIRCUIT DESCRIPTION

DTC Detecting 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 signal to ECM. Then the ECM cancels operation of the lock-up clutch while braking is in progress.

Wiring Diagram:

Step 1:

Step 1 (Continued) - 3:

INSPECTION PROCEDURE

CHECK FOR INTERMITTENT PROBLEMS
LEXUS hand-held tester only:
By putting the vehicle's ECM in the check mode, 1 trip detection logic is possible instead of 2 trip detection logic and sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
1. Clear the DTCs.
2. Set the check mode.
3. Perform a simulation test.
4. Check the connector and terminal.
5. Check the connector connection.