Engine Control System

DTC P1520 STOP LIGHT SWITCH CIRCUIT MALFUNCTION

CIRCUIT DESCRIPTION

DTC Detecting Condition:

This signal is used to detect that the brakes have been applied. The STP signal voltage is the same as the one supplied to the stop lights.

The STP signal is used mainly to control the fuel cut-off engine speed (The fuel cut-off engine speed is reduced slightly when the vehicle is braking.).

Wiring Diagram:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the 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.

Step 1 - 2:

Step 3:

Hand-held tester

Step 1 - 2:

Step 3:

OBD II scan tool (excluding hand-held tester)

CHECK FOR INTERMITTENT PROBLEMS

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 the sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.

1. Clear the DTC.
2. Set the check mode .
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.