LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chrysler >> 2001 >> Intrepid ES >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1391: Intermittent Loss Of CMP Or CKP >> Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P1391: Intermittent Loss Of CMP Or CKP: Testing

NOTE: CMP or CKP sensor signal loss can be detected by an RPM change, DTC or by observing oscilloscope pattern. Refer to manufacturer's operation manual for instructions in use of oscilloscope and procedure for pattern analysis.
  1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and equal to zero, go to next step. If GOOD TRIP counter is not displayed and equal to zero, go to step  10 .
  2. Turn ignition off. Ensure CMP sensor connector is connected. See Figure or Figure . Using oscilloscope connected to ground, backprobe CMP sensor signal circuit (Tan/Yellow wire) at CMP sensor 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  6 .
  3. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. Ensure CMP sensor and/or CKP sensor mounting bolts are tight. Check for any technical service bulletins that may apply. If no problems are found, go to next step.
  4. Ensure ignition is off. Remove CMP sensor. Inspect tone wheel/pulse ring for damage or looseness. Repair or replace tone wheel/pulse ring as necessary. If tone wheel/pulse ring is okay, go to next step.
  5. If no other possible causes are remaining, CMP sensor is assumed to be defective. Replace CMP sensor.
  6. Turn ignition off. Ensure CKP sensor connector is still connected. See Figure . Using oscilloscope connected to ground, backprobe CKP sensor signal circuit (Gray/Black wire) at CKP sensor connector. 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  10 .
  7. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. Ensure CMP sensor and/or CKP sensor mounting bolts are tight. Check for any technical service bulletins that may apply. If no problems are found, go to next step.
  8. Remove CKP sensor. Inspect tone wheel/flexplate for damage, foreign material or excessive movement. Repair or replace tone wheel/flexplate as necessary. If tone wheel/flexplate is okay, go to next step.
  9. If no other possible causes are remaining, CKP sensor is assumed to be defective. Replace CKP sensor.
  10. Turn ignition off. Using oscilloscope connected to ground, backprobe CKP signal circuit (Gray/Black wire) at terminal No. 32 at PCM C1 connector. See Figure and Figure . Turn ignition on and observe oscilloscope pattern. If CKP sensor did not generate any pulses, go to next step. If CKP sensor generated any pulses, replace CKP sensor.
  11. Turn ignition off. Using oscilloscope connected to ground, backprobe CMP signal circuit (Tan/Yellow wire) at terminal No. 33 at PCM C1 connector. Turn ignition on and observe oscilloscope pattern. If CMP sensor did not generate any pulses, go to next step. If CMP sensor generated any pulses, replace CMP sensor.
  12. Turn ignition off. Using oscilloscope connected to ground, backprobe CKP signal circuit (Gray/Black wire) at terminal No. 32 at PCM C1 connector. Start engine. Observe oscilloscope pattern while wiggling related wiring harness and connectors. If no irregularities in oscilloscope pattern exist, go to next step. If any irregularities in oscilloscope pattern exist, carefully inspect harness connectors. Repair connectors as necessary. If connectors are okay, replace CKP sensor.
  13. Turn ignition off. Using oscilloscope connected to ground, backprobe CMP signal circuit (Tan/Yellow wire) at terminal No. 33 at PCM C1 connector. Start engine. Observe oscilloscope pattern while wiggling related wiring harness and connectors. If no irregularities in oscilloscope pattern exist, go to next step. If any irregularities in oscilloscope pattern exist, carefully inspect harness connectors. Repair connectors as necessary. If connectors are okay, replace CMP sensor.
  14. Conditions that set DTC are not present at this time. Perform the following to help identify intermittent condition:
    • With engine running at normal operating temperature, wiggle related wiring harness while monitoring related parameters on scan tool. If voltage changes or DTC sets while wiggling wiring harness, repair connectors or wiring harness where wiggling caused voltage to change or DTC to set.
    • Review freeze frame information on scan tool. Duplicate conditions present when DTC was set.
    • Refer to any technical service bulletins that may apply.
    • Visually inspect related wiring harness. Check for chafed, pierced, pinched or partially broken wires.
    • Visually inspect related wiring harness connectors. Check for broken, bent, pushed out or corroded terminals.

    If a problem is found, repair as necessary. If no problems are found, test is complete.

scientia non olet · About LEMON Manuals