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Jeep Liberty KJ. Manual - part 641

Possible Causes

NO START PRE-TEST

POWERTRAIN FUSES OPEN

SECONDARY INDICATORS PRESENT

ENGINE MECHANICAL PROBLEM

(F142) ASD RELAY OUTPUT CIRCUIT OPEN

FUEL CONTAMINATION

Diagnostic Test

NO START PRE-TEST

NOTE: The following list of items must be checked before continuing with any no start tests.
The battery must be fully charged and in good condition. A low charged battery may produce invalid test results. If
the battery is low, charge the battery and then attempt to start the vehicle by cranking the engine for 15 seconds,
3 consecutive times.

This will allow any DTCs to set that may have been erased due to a dead battery.

Try to communicate with PCM if not able to communicate check fuses.

Make sure the Powers and Ground to the PCM are OK.

Make sure the PCM communicates with the scan tool and that there are no DTCs stored in the PCM memory. If the
PCM reports a No Response condition, refer to section 8 Electrical Electronic Control Module Electrical Diagnostics
for the proper tests.

Read the PCM DTCs with the scan tool. If any DTCs are present, they must be repaired before continuing with any
other No Start diagnostic tests. Refer to the Table of Contents for the related P-code that is reported by the PCM.

Make sure that the Bus is functional. Attempt to communicate with the Instrument Cluster and VTSS, If you are
unable to establish communications refer to 8 Electrical Electronic Control Module Electrical Diagnostics for the
proper Diagnostic procedures.

The Sentry Key Immobilizer System must be operating properly. Check for proper communication with the scan tool
and check for DTCs that may be stored in the Sentry Key Immobilizer Module (SKREEM). Repair the DTC(s) before
continuing.

If no DTCs are found, using the scan tool, select Clear PCM (BATT Disconnect).

Crank the engine several times. Using the scan tool, read DTCs. If a DTC is present perform the DTC diagnostics
before continuing.

Were any problems found?

Yes

>> Repair as necessary.

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

>> Go To 2

OPEN FUSE

Check for any open fuses in the IPM or Junction Block that may be related to the No Start condition.

Are any of the fuses open?

Yes

>> Replace the open fuse and check the related circuit(s) for a short to ground.

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

>> Go To 3

9 - 622

ENGINE ELECTRICAL DIAGNOSTICS

SECONDARY INDICATORS PRESENT

Ignition on, engine not running.

With the scan tool, under DTCs & Related Functions, read the Secondary Indicators while cranking the engine.

Are there any Secondary Indicators present while cranking the engine?

Yes

>> Refer to the Engine Electrical Diagnostics group and perform the tests related to the secondary indicator

that is reported by the scan tool.

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

>> Go To 4

POSSIBLE MECHANICAL PROBLEMS

Check for any of the following conditions/mechanical problems.

ENGINE VALVE TIMING - must be within specifications, check for broken timing components

ENGINE COMPRESSION - must be within specifications

ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.

Are there any engine mechanical problems?

Yes

>> Repair as necessary.

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

>> Go To 5

(F142) ASD RELAY OUTPUT CIRCUIT OPEN

Turn the ignition off.

Remove the ASD relay from the PDC.

Disconnect the C3 PCM harness connector.

Verify the ASD Relay is getting voltage on the Fused B+ circuits before
continuing.

CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller Special Tool #8815
to perform diagnosis.
Measure the resistance of the ASD Relay Output circuit from the ASD
Relay connector to the appropriate terminals of special tool #8815, Igni-
tion coil, and the fuel injectors.

Is the resistance below 5.0 ohms?

Yes

>> Go To 6

>> Repair the open in the (F142) ) ASD Relay Output circuit.

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

FUEL PUMP DELIVERY

Verify that the Fuel tank is not empty before continuing.

Follow the diagnostics for Checking Fuel Delivery in Section 9 Engine Electrical Diagnostic section of this manual.

Was the No Start condition solved after following the above diagnostic test?

Yes

>> Test Complete.

>> Check for contamination/water in the fuel. Make sure the fuel being used in this vehicle meets manu-

factures Fuel Requirement, refer to the service manual.

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

ENGINE ELECTRICAL DIAGNOSTICS

9 - 623

*FUEL PRESSURE LEAK DOWN

For a complete wiring diagram Refer to Section 8W.

Possible Causes

FAULTY FUEL PUMP MODULE

FUEL INJECTOR(S)

Diagnostic Test

FUEL PUMP MODULE

NOTE: Before continuing visually and physically inspect the fuel delivery system for external leaks or dam-
age. Repair / replace as necessary.
Turn the ignition off.

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow
these instructions can result in personal injury or death.
Install special tool #6539 (5/16

) or #6631 (3/8

) fuel line adapter.

Install the fuel pressure gauge.

Start the engine and allow the fuel system to reach maximum pressure.

Turn the ignition off.

NOTE: Fuel specification is 407 KPa +/- 34 KPa (59 psi +/- 5 psi).
Using special tool #C4390, Hose Clamp Pliers, pinch the rubber fuel line between the fuel pressure gauge and the
engine.

Monitor the fuel pressure gauge for a minimum of 5 minutes.

NOTE: The pressure should not fall below 241 KPa (35 psi)

Does the fuel pressure drop?

Yes

>> Replace Fuel Pump Module.

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

>> Go To 2

FUEL INJECTOR(S)

Start the engine and allow the fuel system to reach maximum pressure.

Turn the ignition off.

NOTE: NOTE: Fuel specification is 407 KPa +/- 34 KPa (59 psi +/- 5 psi).
Move special tool #C4390, Hose Clamp Pliers, from between the fuel pressure gauge and the engine to between
the fuel pressure gauge and fuel pump module.

Monitor the fuel pressure gauge for a minimum of 5 minutes.

NOTE: The pressure should not fall below 241 KPa (35 psi)

Does the fuel pressure drop?

Yes

>> Replace the leaking fuel injectors.

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

>> Test Complete.

9 - 624

ENGINE ELECTRICAL DIAGNOSTICS

*NO CRANK CONDITION

For a complete wiring diagram Refer to Section 8W.

Possible Causes

MECHANICAL CONDITION

BATTERY CIRCUIT RESISTANCE TOO HIGH

FUSED IGNITION SWITCH OUTPUT CIRCUITS

FUSED B+ CIRCUIT OPEN

(T752) STARTER RELAY CONTROL CIRCUIT OPEN

(T750) STARTER RELAY OUTPUT CIRCUIT OPEN

TRANSMISSION RANGE SENSOR

STARTER RELAY

STARTER

Diagnostic Test

MECHANICAL CONDITION

NOTE: Verify the battery is fully charged and capable of passing a load test before continuing.

WARNING: Make sure the battery is disconnected, then wait two minutes before proceeding. Failure to do
so may result in personal injury or possible death.
Turn the engine over by hand to make sure the engine is not seized.

Is the engine able to turn over?

Yes

>> Go To 2

>> Repair the mechanical condition preventing the starter motor from cranking.

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

TRANSMISSION RANGE SENSOR

Turn the ignition off.

Disconnect the TRS harness connectors.

Move the Gear selector through all gear positions, from Park to 1st and back.

While moving the gear selector through each gear, measure the resistance between ground and the TRS (T41)
Sense (P/NSense) circuit at the TRS connector.

NOTE: The circuit is grounded in Park and Neutral and open in the other positions.

Did the resistance change from above 100 kohms (open) to below 10.0 ohms (grounded) ?

Yes

>> Go To 3

>> Replace the Transmission Range Sensor.

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

ENGINE ELECTRICAL DIAGNOSTICS

9 - 625

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