Circuit Description

Park/neutral position switch is on whenever shift lever is in "N" or "P" position. With switch on, ECM terminal NSW is grounded via starter relay (zero voltage at terminal NSW). With shift lever in "D", "2", "L" or "R" position, switch is off (battery voltage at terminal NSW). 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.