Engine Control System

DTC P1780 Park/Neutral Position Switch Malfunction

CIRCUIT DESCRIPTION

DTC Detection Condition:

The park/neutral position switch goes on when the shift lever is in the N or P shift position. When it goes on, terminal NSW of the ECM is grounded to the body ground via the starter relay, thus the terminal NSW voltage becomes 0 V. When the shift lever is in the D, 2, L or R position, the park/neutral position switch goes off, so the voltage of the ECM. Terminal NSW becomes battery voltage and the voltage of the ECM internal power source. If the shift lever is moved from the N position to the D position, this signal is used for air-fuel ratio correction and for idle speed control (estimated control), etc.

HINT: After confirming DTC P1780, use the TOYOTA hand-held tester to confirm the park/neutral position switch signal from the CURRENT DATA.

Wiring Diagram:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, this 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 2 (Continued) - 3:

TOYOTA hand-held tester

Step 1:

Step 2:

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