DTC P1899: P/N Switch Performance (4.0L A/T): Testing

Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1899 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1899 or displayed count is not "0", go to step 7 .
Apply parking brake. Turn ignition on. Using scan tool, monitor PNP switch input state while moving shift lever from Park to 1st, then back to Park. If scan tool did not indicate correct gear shift positions, go to next step. If scan tool indicated correct gear positions, no problem is indicated at this time. Test is complete.
Ensure ignition is off. Disconnect PNP switch connector located on side of transmission. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Brown/Yellow wire between PNP switch harness connector and terminal No. 6 at PCM C1 harness connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/Yellow wire.
Measure resistance between ground and terminal No. 6 (Brown/Yellow wire) at PCM C1 connector. See Figure . If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/Yellow wire between PNP switch and PCM.
Reconnect PNP switch connector. Measure resistance between ground and terminal No. 6 (Brown/Yellow wire) at PCM C1 connector while moving shift lever from Park to 1st, then back to Park. If resistance changes from more than 10 ohms to less than 10 ohms, go to next step. If resistance does not change from more than 10 ohms to less than 10 ohms, PNP switch is stuck or defective. Replace PNP switch.
At this time PCM is assumed to be defective. Replace PCM.
At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P1899: P/N SWITCH PERFORMANCE is present, go to step 2 . If DTC P1899: P/N SWITCH PERFORMANCE is not present, no problem is indicated at this time. Check for any related technical service bulletins that may apply.