Content .. 136 137 138 139 ..

Jeep Wrangler TJ. Manual - part 138

TEST

ACTION

APPLICABILITY

If there are no possible causes remaining, view repair.

All

Repair

Replace the Fuel Pump Module.
Perform POWERTRAIN VERIFICATION TEST VER - 1.

Turn the ignition off.
Remove the Fuel Pump Relay from the PDC.
Using a 12-volt test light connected to ground, backprobe the Fuel Pump Relay Fused
B+ circuit at the PDC.
Does the test light illuminate?

All

Yes

→ Go To 9

→ Repair the open or short to ground in the (A61) Fuel Pump Realy

Fused B+ circuit. Inspect the fuse and repair as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 1.

Disconnect the Fuel Pump Module harness connector.
Measure the resistance of the (A141) Fuel Pump Relay Output circuit from the relay
connector to the Fuel Pump Module connector.
Is the resistance below 5.0 ohms?

All

Yes

→ Replace the Fuel Pump Relay.

Perform POWERTRAIN VERIFICATION TEST VER - 1.

→ Repair the open in the (A141) Fuel Pump Relay Output circuit.

Perform POWERTRAIN VERIFICATION TEST VER - 1.

277

STARTING

*CHECKING FUEL DELIVERY —

Continued

Symptom:

*CHECKING HARD START (FUEL DELIVERY SYSTEM)

POSSIBLE CAUSES

RESTRICTED FUEL SUPPLY LINE

FUEL PUMP MODULE

FUEL PUMP INLET STRAINER PLUGGED

FAULTY FUEL PUMP MODULE

FUEL INJECTORS

FUEL CONTAMINATION

TEST

ACTION

APPLICABILITY

Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Install the fuel pressure gauge at the engine. Refer to the Service Information FUEL
DELIVERY Section.
Ignition on, engine not running.
With the DRBIII

t, actuate the ASD Fuel System test and observe the fuel pressure

gauge.
NOTE: Fuel pressure specification is 400 KPa +/- 34 KPa (58 psi +/- 5 psi).
Choose a conclusion that best matches your fuel pressure reading.

All

Below Specification

Go To

Within Specification

Go To

Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Raise vehicle on hoist, and disconnect the fuel supply line at the fuel pump module.
Install special tool #6539 (5/16

9) fuel line adapter fuel pressure gauge between the

fuel supply line and the fuel pump module.
Ignition on, engine not running.
With the DRBIII

t, actuate the ASD Fuel System test and observe the fuel pressure

gauge.
NOTE: Fuel pressure specification is 400 KPa +/- 34 KPa (58 psi +/- 5 psi).
Is the fuel pressure within specification?

All

Yes

→ Visually and physically inspect the fuel supply lines between the

fuel tank and the fuel rail. Repair/replace as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 2.

→ Go To 3

278

STARTING

TEST

ACTION

APPLICABILITY

Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose,fitting or line,
the fuel system pressure must be released.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?

All

Yes

→ Replace the Fuel Pump Inlet Strainer.

Perform POWERTRAIN VERIFICATION TEST VER - 2.

→ Test Complete.

NOTE: Before continuing visually and physically inspect the fuel delivery
system for external leaks or damage. 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 servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Install special tool #6539 (5/16

9) 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 400 KPa +/- 34 KPa (58 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?

All

Yes

→ Replace fuel pump module.

Perform POWERTRAIN VERIFICATION TEST VER - 2.

→ Go To 5

WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Remove special tool #C4390.
Start the engine and allow the fuel system to reach maximum pressure.
Turn the ignition off.
NOTE: Fuel specification is 400 KPa +/- 34 KPa (58 psi +/- 5 psi).
Install special tool #C4390, Hose Clamp Pliers, pinch the rubber fuel line between the
fuel pressure gauge and the 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?

All

Yes

→ Replace leaking fuel injectors.

Perform POWERTRAIN VERIFICATION TEST VER - 2.

→ Check the fuel for contaminants.

Perform POWERTRAIN VERIFICATION TEST VER - 2.

279

STARTING

*CHECKING HARD START (FUEL DELIVERY SYSTEM) —

Continued

Symptom:

*ENGINE CRANKS DOES NOT START

POSSIBLE CAUSES

NO START PRE-TEST

POWERTRAIN FUSES OPEN

SECONDARY INDICATORS PRESENT

NO CKP SENSOR SIGNAL WHEN CRANKING ENGINE

NO CMP SENSOR SIGNAL WHEN CRANKING ENGINE

ENGINE MECHANICAL PROBLEM

(A142) ASD RELAY OUTPUT CIRCUIT OPEN

FUEL CONTAMINATION

TEST

ACTION

APPLICABILITY

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 DRBIII

t and that there are no DTCs

stored in the PCM memory. If the PCM reports a No Response condition, refer to the
Communication category for the proper tests.
Read the PCM DTCs with the DRBIII

t. If any DTCs are present, they must be

repaired before continuing with any other No Start diagnostic tests. Refer to the
Symptom list for the related P-code that is reported by the PCM.
Make sure that the PCI bus is functional. Attempt to communicate with the
Instrument Cluster and VTSS. If you are unable to establish communicate refer to
the Communication category for the proper symptoms.
The Sentry Key Immobilizer System must be operating properly. Check for proper
communication with the DRBIII

t and check for DTCs that may be stored in the

Sentry Key Immobilizer Module (SKIM). Repair the DTC(s) before continuing.
If no DTCs are found, using the DRBIII

t, select Clear PCM (BATT Disconnect).

Crank the engine several times. Using the DRBIII

t, read DTCs. If a DTC is present

perform the DTC diagnostics before continuing.
Were any problems found?

All

Yes

→ Repair as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 5.

→ Go To 2

Check for any open fuses in the PDC or Junction Block that may be related to the No
Start condition.
Are any of the fuses open?