P1391

Tests 1 - 2:

Tests 3 - 7:

Tests 8 - 11:

Tests 12 - 15:

Test 16:

SYMPTOM
P1391 - INTERMITTENT LOSS OF CMP OR CKP

WHEN MONITORED
Engine running or cranking.

SET CONDITION
When the failure counter reaches 20 for 2 consecutive trips.

POSSIBLE CAUSES
- CMP sensor out of sync
- Damaged tone wheel/flexplate (crankshaft)
- Damaged tone wheel/pulse ring (camshaft)
- Irregular lab scope pattern of CMP signal
- Wiring harness intermittent problem
- intermittent problem CKP signal loss when wiring is wiggled
- Irregular lab scope pattern of CKP signal
- Intermittent CMP signal loss when wiring is wiggled
- Sensor connector/wiring
- Camshaft Position Sensor
- Crankshaft Position Sensor