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Jeep Liberty KJ. Manual - part 540

12.

(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (F856) 5-volt Supply
circuit in the CMP Sensor harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (F856) 5-volt Supply cir-

cuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)

>> Go To 13

13.

PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.

Were there any problems found?

Yes

>> Repair as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Replace and program the Powertrain Control Module per Service Information.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

14.

ERRATIC CMP SIGNAL

With a lab scope probe and the Miller special tool #6801, back probe the (K44) CMP Signal circuit in the CMP
harness connector.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands
near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in
personal injury or death.
Ignition on, engine not running.

Wiggle the related wire harness and lightly tap the Camshaft Position Sensor.

Observe the lab scope screen.

Allow the engine to idle.

Observe the lab scope screen.

Did the CMP Sensor generate any erratic pulses?

Yes

>> Replace the Camshaft Position Sensor.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Go To 15

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ENGINE ELECTRICAL DIAGNOSTICS

15.

ERRATIC CKP SIGNAL

Turn the ignition off.

With a lab scope probe and the Miller special tool #6801, backprobe the (K24) CKP Signal circuit in the CKP har-
ness connector.

Wiggle the related wire harness and lightly tap on the Crankshaft Position Sensor.

Observe the lab scope screen.

Allow the engine to idle.

Observe the lab scope screen.

Did the CKP Sensor generate any erratic pulses?

Yes

>> Replace the Crankshaft Position Sensor.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Test Complete.

ENGINE ELECTRICAL DIAGNOSTICS

9 - 319

P0344-CAMSHAFT POSITION SENSOR INTERMITTENT

For a complete wiring diagram Refer to Section 8W.

9 - 320

ENGINE ELECTRICAL DIAGNOSTICS

•

When Monitored:
While cranking the engine and engine running.

•

Set Condition:
When the failure counter reaches 20. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes

(F856) 5-VOLT SUPPLY CIRCUIT OPEN

(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

(K44) CMP SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

(K44) CMP SIGNAL CIRCUIT OPEN

(K44) CMP SIGNAL CIRCUIT SHORTED TO GROUND

(K44) CMP SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT

TONE WHEEL/PULSE RING

CAMSHAFT POSITION SENSOR

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

ACTIVE DTC

Ignition on, engine not running.

With a scan tool, read DTCs.

Is the DTC active at this time?

Yes

>> Go To 2

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

CHECKING CAMSHAFT POSITION SENSOR SIGNAL WITH A LAB SCOPE

Turn the ignition off.

With a lab scope probe and the Miller special tool #6801, backprobe the (K44) CMP Signal circuit in the CMP
harness connector.

Observe the lab scope screen.

Start the engine.

Observe the lab scope screen.

Are there any irregular or missing signals?

Yes

>> Go To 3

>> Go To 8

ENGINE ELECTRICAL DIAGNOSTICS

9 - 321

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