| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. |
Circuit Description
Park/neutral position switch is on whenever shift lever is in "N" or "P" position. With shift lever in "D", "2", "L" or "R" position, switch is off. DTC P1780 is set when 2 or more switches are on simultaneously in any gear position. DTC P1780 is also set when park/neutral position switch is on while driving vehicle for 30 seconds or more at 44 MPH or more and engine speed at 1500-2500 RPM. Possible causes are
- Short in Park/Neutral Position (PNP) switch circuit.
- Faulty PNP switch.
- Faulty ECM.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.