Jeep Grand Cherokee WJ. Manual - part 1020

TEST

ACTION

APPLICABILITY

At this time the Speed Control Switch and Servo functions appear to operate
properly.
Using the DRBIII

t, monitor the Speed Control OUTPUT status.

Road test the Vehicle at speeds over 35 MPH (55kmh) and attempt to set the Speed
Control.
The following items will not allow the Speed Control to set. The last or most recent
cause for Speed Control not to set is indicated by the DENIED status.
If ON/OFF Denied message is indicated, the Powertrain Control Module does not see
an ON signal from the Switch.
If SPEED Denied message is indicated, the Vehicle Speed as seen by the Powertrain
Control Module is not greater than 36 MPH.
If RPM Denied message is indicated, the Engine RPM is excessively high.
If BRAKE Denied message is indicated, the Brake Switch Sense Circuit is open
indicating to the PCM that the Brakes are applied. The Sense Circuit is grounded
through the Brake Pedal Switch when the brakes are released.
If P/N Denied message is indicated, Park/Neutral Switch Sense Circuit is grounded
indicating to PCM that Transmission is not in gear. The Sense Circuit is grounded
through the P/N Switch when Transmission is in Park or Neutral.
If RPM/SPD Denied message is indicated, the PCM senses excessive Engine RPM for
a given Vehicle speed.
If SOL FLT Denied message is indicated, the Powertrain Control Module senses a
Servo Solenoid Circuit trouble code that is maturing or set in memory.
Continue if the previous instructions have been completed.

All

Repair

Test Complete.

297

SPEED CONTROL

*CHECKING SPEED CONTROL OPERATION WITH NO DTC’S PRESENT
—

Continued

Symptom:

*ENGINE CRANKS DOES NOT START

POSSIBLE CAUSES

NO START PRE-TEST

SECONDARY INDICATORS PRESENT

POWERTRAIN FUSES OPEN

FUEL PUMP INLET STRAINER PLUGGED

NO CKP SENSOR SIGNAL WHEN CRANKING ENGINE

NO CMP SENSOR SIGNAL WHEN CRANKING ENGINE

FUEL PUMP GROUND CIRCUIT OPEN

FUEL PUMP RELAY OUTPUT CIRCUIT OPEN

FUEL PUMP MODULE

KINKED/RESTRICTED FUEL SUPPLY LINE

CKP & CMP SENSORS OUT OF SYNC

FUEL PUMP MODULE

FUEL FILTER/PRESSURE REGULATOR (HIGH)

FUEL PUMP CAPACITY (VOLUME) OUT OF SPECS

ENGINE MECHANICAL PROBLEM

298

STARTING

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 DTC’s to set that may have been erased due to a dead battery.
Ensure the Powers and Ground to the PCM are ok.
Make sure the PCM communicates with the DRBIII

t and that there are no DTC’s

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 DTC’s with the DRBIII

t. If any DTC’s 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.
Ensure that the PCI bus is functional. Attempt to communicate with the Instrument
Cluster and SKIM, 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 DTC’s that may be stored in the

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

t select Clear PCM (BATT Disconnect).

Crank the engine several times. Using the DRBIII

t, read DTC’s. 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

Turn the ignition on.
With the DRBIII

t, under DTC’s & Related Functions, read the Secondary Indicators

while cranking the engine.
Are there any Secondary Indicators present while cranking the engine?

All

Yes

→

Refer to symptom list and perform tests related to the secondary
indicator that is reported by the DRBIII

Perform POWERTRAIN VERIFICATION TEST VER - 5.

→

Go To

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?

All

Yes

→

Replace the open fuse and check the related circuit(s) for a short
to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.

→

Go To

With the DRBIII

t in Sensors, check the 9Current CKP Count9 while cranking the

engine.
Does the CKP Counter change while cranking the engine?

All

Yes

→

Go To

→

Refer to Driveability Symptom P0320-NO CRANK REFERENCE
SIGNAL AT PCM.
Perform POWERTRAIN VERIFICATION TEST VER - 5.

299

STARTING

*ENGINE CRANKS DOES NOT START —

Continued

TEST

ACTION

APPLICABILITY

Is the vehicle equipped with a 4.7 litre engine?

All

→

Go To

Yes

→

Go To

With the DRBIII

t in Sensors, check the 9Current CMP Count9 while cranking the

engine.
Does the

9Current CMP Count9 change while cranking the engine?

All

Yes

→

Go To

→

Refer to Driveability Symptom P0340-NO CAM SIGNAL AT PCM
Perform POWERTRAIN VERIFICATION TEST VER - 5.

Turn the ignition on.
With the DRBIII

t in Inputs/Outputs, check the 9Current Sync State9 while cranking

the engine.
Does the DRBIII

t show Current Sync State 9Out of Sync9 while cranking the engine?

All

Yes

→

Check for the CKP Sensor Signal ckt shorted to the CMP Sensor
Signal ckt OR Check for valve timing/CMP drive problem.
Perform POWERTRAIN VERIFICATION TEST VER - 5.

→

Go To

With the DRBIII

t in Sensors, check the 9Current CMP Count9 while cranking the

engine.
Does the

9Current CMP Count9 change while cranking the engine?

All

Yes

→

Go To

→

Refer to Driveability Symptom P0340-NO CAM SIGNAL AT PCM
Perform POWERTRAIN VERIFICATION TEST VER - 5.

Turn the ignition on.
With the DRBIII

t in Inputs/Outputs, check the 9Current Sync State9 while cranking

the engine.
Does the DRBIII

t show Current Sync State 9Out of Sync9 while cranking the engine?

All

Yes

→

Check for the CKP Sensor Signal ckt shorted to the CMP Sensor
Signal ckt OR Check for valve timing/CMP drive problem.
Perform POWERTRAIN VERIFICATION TEST VER - 5.

→

Go To

NOTE: This test applies only to 4.7L engine.
Turn the ignition off.
Disconnect the spark plug cable at the #1 spark plug.
Connect the #1spark plug cable to a spark tester and the spark tester to a good engine
ground.
Caution: Ignition coil damage may occur if the spark tester is not properly
grounded.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
While cranking the engine for 10 seconds, watch for spark at the spark tester.
Note: Consider 1 or 2 sparks as a no spark condition.
Is there good spark while cranking the engine?

All

Yes

→

Go To

→

Go To

300

STARTING

*ENGINE CRANKS DOES NOT START —

Continued

Content .. 1018 1019 1020 1021 ..