DTC P1391: Intermittent Loss Of CMP Or CKP: Testing

Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1391 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P1391 is not displayed or displayed count is not "0", go to step 14 .
Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, select MISCELLANEOUS, then SET SYNC. Ensure engine is at normal operating temperature. Observe ACTUAL SYNC SETTING on scan tool display. If scan tool displays IN RANGE, go to next step. If scan tool does not display IN RANGE, locate CMP sensor. CMP sensor is mounted on top of oil pump drive shaft assembly and is located on right side of engine, near oil filter. Loosen oil pump drive shaft assembly hold-down clamp bolt and rotate oil pump drive shaft assembly until reading is as close to zero degrees as possible, and IN RANGE message is displayed. Tighten hold-down clamp bolt to 17 ft. lbs. (23 N.m).
Turn ignition off. Using oscilloscope's voltage lead, backprobe Tan/Yellow wire at CMP sensor harness connector. Start engine and observe oscilloscope pattern. If CMP sensor signal pattern is not consistent, go to next step. If CMP sensor signal pattern is consistent, go to step 5 .
Turn ignition off. Disconnect CMP sensor connector. Disconnect PCM connectors. PCM is located in engine compartment on left front fender, near radiator support. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, go to next step.
Remove CMP sensor from oil pump drive shaft assembly. Inspect tone wheel/pulse ring for damage. Repair or replace tone wheel/pulse ring as necessary. If tone wheel/pulse ring is okay, go to next step.
At this time, CMP sensor is assumed to be defective. Replace CMP sensor.
Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 8 (Gray/Black wire) at PCM C1 harness connector. See Figure . PCM is located in engine compartment on left front fender, near radiator support. Start engine and observe oscilloscope pattern. If CKP sensor signal pattern is not consistent, go to next step. If CKP sensor signal pattern is consistent, go to step 11 .
Turn ignition off. Disconnect CKP sensor connector. CKP sensor is mounted to left side of transmission bellhousing. CKP sensor connector is located on top of intake manifold, near firewall. Visually inspect connector for corroded, damaged, pushed-out or miswired terminals. Repair connector as necessary. If connector is okay, check if CKP sensor mounting bolts/nuts are tight. Tighten mounting bolts/nuts as necessary. See TORQUE SPECIFICATIONS in REMOVAL, OVERHAUL & INSTALLATION article. If mounting bolts/nuts are tight, go to next step.
Turn ignition off. Remove CKP sensor. Inspect notches on flywheel/drive plate for damage or debris. Flywheel/drive plate contains 3 sets of notches which contain 4 slots in each set. Check slotted areas for damage or any foreign debris. If slotted areas on flywheel/drive plate are okay and no debris exists, go to next step. If slotted areas on flywheel/drive plate are damaged or debris exists, repair or replace flywheel/drive plate as necessary.
At this time, CKP sensor is assumed to be defective. Replace CKP sensor.
Turn ignition off. Visually inspect CMP sensor and/or CKP sensor connector for corroded, damaged, pushed-out or miswired terminals. Repair connector as necessary. If connector is okay, check if CMP sensor and/or CKP sensor mounting bolts/nuts are tight. Tighten mounting bolts/nuts as necessary. See TORQUE SPECIFICATIONS in REMOVAL, OVERHAUL & INSTALLATION article. If mounting bolts/nuts are tight, go to next step.
Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 8 (Gray/Black wire) at PCM C1 harness connector. See Figure . PCM is located in engine compartment on left front fender, near radiator support. Start engine. While monitoring oscilloscope pattern, wiggle wiring harness from CKP sensor to PCM. If CKP sensor signal pattern does not remain consistent while wiggling wiring harness, repair wiring harness where wiggling caused CKP sensor signal pattern to become inconsistent. If CKP sensor signal pattern remains consistent while wiggling wiring harness, go to next step.
Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 18 (Tan/Yellow wire) at PCM C1 harness connector. See Figure . PCM is located in engine compartment on left front fender, near radiator support. Start engine. While monitoring oscilloscope pattern, wiggle CMP sensor signal circuit from CMP sensor to PCM. If CMP sensor signal pattern is consistent, no problem is indicated at this time. Test is complete. If CMP sensor signal pattern is not consistent, repair wiring harness where wiggling caused oscilloscope pattern to become inconsistent.
Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 18 (Tan/Yellow wire) at PCM C1 harness connector. See Figure . PCM is located in engine compartment on left front fender, near radiator support. Start engine. While monitoring oscilloscope pattern, wiggle CMP sensor signal circuit from CMP sensor to PCM. If CMP sensor signal pattern is consistent, go to next step. If CMP sensor signal pattern is not consistent, repair wiring harness where wiggling caused oscilloscope pattern to become inconsistent.
Turn ignition off. Visually inspect related wiring harness and connectors. Repair wiring harness and connectors as necessary. If wiring harness and connectors are okay, go to next step.
Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 8 (Gray/Black wire) at PCM C1 harness connector. See Figure . PCM is located in engine compartment on left front fender, near radiator support. Start engine. While monitoring oscilloscope pattern, wiggle wiring harness from CKP sensor to PCM. If CKP sensor signal pattern does not remain consistent while wiggling wiring harness, repair wiring harness where wiggling caused CKP sensor signal pattern to become inconsistent. If CKP sensor signal pattern remains consistent while wiggling wiring harness, no problem is indicated at this time. Test is complete.