Here is some info I have gathered. Suspect Crankshaft Position or Camshaft Position Sensor issues. Don't overlook wiring issues or poor ground wire connections to either sensor.
Google Scan Tools, O-Scopes and Toothpicks
, and read the article.
Buy genuine Jeep sensors, cheap crappy Chinese sensors (many of which have a "Lifetime Warranty") are often weak, out of specification, or even failed right out of the box.
- Intermittent Loss of CMP or CKP Signal. Loss of the Cam Position Sensor or Crank Position sensor signal has occurred.
P1391 – Possible symptoms:
(1) random misfire/stumble/stalling, often over bumps or right turns and when going into reverse.
(2) shorted out the Fuel pump/ECU power wire.
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.
P1391-INTERMITTENT LOSS OF CMP OR CKP
CMP SENSOR OUT OF SYNC
-DAMAGED TONE WHEEL/FLEX PLATE (CRANKSHAFT)
-DAMAGED TONE WHEEL/PULSE RING (CAMSHAFT)
-IRREGULAR LAB SCOPE PATTERN OF CMP SIGNAL
INTERMITTENT CKP SIGNAL LOSS WHEN WIRING IS WIGGLED
-IRREGULAR LAB SCOPE PATTERN OF CKP SIGNAL
-WIRING HARNESS INTERMITTENT
INTERMITTENT CMP SIGNAL LOSS WHEN WIRING IS WIGGLED
-CAMSHAFT POSITION SENSOR
-CKP SENSOR CONNECTOR/WIRING
-CRANKSHAFT POSITION SENSOR
Inspect your wire harnesses for damaged wires, chafed insulation, or failed wire splices. Use a volts/ohms multi-meter to check the resistance of the ground wire circuits from each sensor. Replace corroded ground wires/connectors and clean ground wire connection points.
Google Scan Tools, O-Scopes and Toothpicks, and read the article.
Timing may off. Re-index the distributor/cam sensor per the FSM instructions, or replace faulty distributor/cam sensor pickup module.
A mis-indexed distributor/cam sensor may exhibit surging, light bucking or intermittent engine misfiring. This will most likely occur when the vehicle is at operating temperature and under a light load at approximately 2,000 rpm. The factory procedure must be used as outlined in the service manual.
Fault In Companion Module. No CCD/J1850 bus messages received at the power train control module (PCM) from the AisinWarner Transmission Control Module (TCM).
P1694 will set if no CCd bus messages are received from PCM for 20 seconds or invalid messages are received for 20 seconds.
-CCD Bus (-) circuit open between PCM and TCM.
-CCD Bus (+) circuit open between PCM and TCM.
-Transmission CCD bus wiring damaged.
(Wiring issues or a faulty TCM should be the first suspects)
No CCD Messages Received From PCM. Bus communication failure to PCM. A "Companion DTC" was set in both the ECM and PCM.
- Faulty Engine control Module (ECM)
- Engine control Module(ECM) harness is open or shorted
- Engine control Module (ECM) circuit poor electrical connection
When the CPS short circuits the engine computer (PCM) shuts down to prevent damage to itself. As a result, there is no communication (P1694).
Disconnect your crankshaft position sensor then put the ignition key in the on position. If the instrument cluster voltage and fuel gauges start to work once the CPS is disconnected, then you know the CPS or CPS wires are shorted and is the root cause of the codes. You can verify this by testing the CPS and checking continuity and voltage on the CPS wires.
P1694 Diagnostic Procedure
1. Using scan tool, clear TCM DTCs. Start engine and let idle for at least 2 minutes. Using scan tool, retrieve TCM DTCs. If DTC P1694 returns, go to next step. If DTC P1694 does not return, go to step 5.
2. Check instrument cluster gauges for proper operation. If fuel gauge and speedometer operate properly, go to next step. If fuel gauge and speedometer do not operate properly, see appropriate INSTRUMENT PANELS article.
3. Turn ignition off. Disconnect Gray PCM harness connector. PCM is located at left front of engine compartment. Disconnect TCM harness connector. Measure resistance of CCD BUS (-) circuit (White/Black wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (-) circuit (White/Black wire). If resistance is 5 ohms or less, go to next step.
4. Measure resistance of CCD BUS (+) circuit (Violet/Brown wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (+) circuit (Violet/Brown wire). If resistance is 5 ohms or less, replace TCM.
5. Conditions necessary to set DTC P1694 are currently not present. Inspect related wiring and harness connectors. See WIRING DIAGRAMS. Repair as necessary. If no problem is found, check for broken, bent, backed-out or corroded terminal pins. Check for chafed, pierced or partially broken wires inside insulation. Repair as necessary.