Park Neutral Position Switch Circuit CIRCUIT DESCRIPTION The park/neutral position switch goes on when the shift lever is in the N or P shift position. When it goes on the terminal NSW of the ECM is grounded to body ground via the starter relay and theft deterrent ECU, 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 ECM terminal NSW becomes positive battery voltage, 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. When the park/neutral position switch is off, code "51" is output in the test mode diagnosis. (This is not abnormal.) WIRING DIAGRAM Engine Control Module B+ 76 NSW E9 7 8 B-W 6 ST 4 B 13 B-W B-W W 1J 1K J2 Ignition Switch J/B No.1 4 1J J/B No.1 4 1B B-W 6 Park/Neutral Position Switch 5 W B B 3 EA1 B 2 2 2 2 5 1 2 Starter Relay 3 2 R/B No.2 1 EA3 B S3 1 Starter ALT MAIN 1 2A 2 B Battery L-O 6 L-O 10 L-O 25 4 W-B IB2 IF2 T13 T7 Theft Deterrent and Door Lock Control ECU P21137