Park Neutral Position Switch: 5.7L
- Install scan tool. Turn ignition on, with engine off. Place transmission in Park. Using scan tool, observe PNP switch parameter. If scan tool displays P-N---, go to next step. If scan tool does not display P-N---, go to step 3.
- Shift transmission into Drive. If scan tool displays -R-OD21, check for intermittent. A PNP switch that does not close or an open in signal circuit may cause engine idle speed to decrease when vehicle is shifted into gear. A PNP switch that will not open or a short to ground in signal circuit will cause EGR system to be inoperative possibly resulting in spark knock. Inspect all related wiring and connectors for poor connections or damage. If scan tool does not display -R-OD21, go to step 6.
- Disconnect PNP switch harness connector. Connect a fused jumper wire between PNP switch signal circuit (Orange/Black wire) and PNP switch ground circuit (Black/White wire) at PNP switch harness connector. If scan tool does not display P-N---, go to next step. If scan tool displays P-N---, go to step 9.
- Connect a fused jumper wire between PNP switch signal circuit (Orange/Black wire) at PNP switch harness connector and chassis ground. If scan tool does not display P-N---, leave jumper wire connected and go to next step. If scan tool displays P-N---, go to step 12.
- Turn ignition off. Disconnect PCM harness connector C1. Using a test light connected to battery voltage, probe PNP signal circuit (Orange/Black wire) at PCM harness connector. If test light does not illuminate, go to step 10. If test light illuminates, go to step 8.
- Disconnect PNP switch harness connector. Using scan tool, observe PNP switch parameter. If scan tool does not display -R-OD21, go to next step. If scan tool displays -R-OD21, go to step 9.
- Turn ignition off. Disconnect PCM harness connector C1. Turn ignition on. If scan tool displays -R-OD21, go to step 11. If scan tool does not display -R-OD21, go to step 14.
- Check for poor connection at PCM. If problem does not exist, go to step 14. If problem exists, repair as necessary and go to step 15.
- Check for poor connection at PNP switch or PNP switch not properly adjusted. If problem does not exist, go to step 13. If problem exists, repair as necessary and go to step 15.
- Repair open in PNP switch signal circuit (Orange/Black wire). After repairs, go to step 15.
- Repair short to ground in PNP switch signal circuit (Orange/Black wire). After repairs, go to step 15.
- Repair open in PNP switch ground circuit (Black/White wire). After repairs, go to step 15.
- Replace PNP switch. After repairs, go to step 15.
- Replace PCM. After repairs, go to next step.
- Operate vehicle within conditions under which symptom was noted. If system operates properly, system is okay. If system does not operate properly, go to step 1.