Jeep Grand Cherokee WJ. Manual - part 637

TEST

ACTION

APPLICABILITY

Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the Output Speed Sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary
Measure the resistance of the Output Speed Sensor ground circuit between the PCM
harness connector and the Output Speed Sensor harness connector.
Is the resistance below 5.0 ohms?

without 45RFE

AUTO TRANS

Yes

→

Go To

→

Repair the Output Speed Sensor negative ground circuit for an
open.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the Output Speed Sensor harness connector.
Check connectors - Clean/repair as necessary
Measure the resistance between ground and the Output Speed Sensor ground circuit.
Is the resistance below 5.0 ohms?

without 45RFE

AUTO TRANS

Yes

→

Repair the Output Speed Sensor ground circuit for a short to
ground.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

→

Go To

without 45RFE

AUTO TRANS

Yes

→

Repair the Output Speed Sensor Signal Positive circuit for a short
to ground.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

→

Go To

Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the Output Speed Sensor harness connector.
Check connectors - Clean/repair as necessary
Measure the resistance of the Output Speed Sensor Signal circuit between the PCM
harness connector and the Output Speed Sensor harness connector.
Is the resistance below 5.0 ohms?

without 45RFE

AUTO TRANS

Yes

→

Go To

→

Repair the Output Speed Sensor Signal circuit for an open.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

104

DRIVEABILITY - DIESEL

P0720-LOW OUTPUT SPD SENSOR RPM, ABOVE 15 MPH —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the Output Speed Sensor harness connector.
Check connectors - Clean/repair as necessary
Ignition on, engine not running.
Measure the voltage of the Output Speed Sensor ground circuit in the Output Speed
Sensor harness connector.
Is there any voltage present?

without 45RFE

AUTO TRANS

Yes

→

Repair the output speed sensor ground (-) circuit for a short to
voltage.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

→

Go To

Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the Output Speed Sensor harness connector.
Ignition on, engine not running.
Measure the voltage of the Output Speed sensor Signal circuit in the Output Speed
Sensor harness connector.
Is there any voltage present?

without 45RFE

AUTO TRANS

Yes

→

Repair the output speed sensor signal (+) circuit for a short to
voltage.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

→

Go To

Turn the ignition off.
Disconnect the Output Speed Sensor harness connector.
Check connectors - Clean/repair as necessary
Measure the resistance between the terminals of the Output Speed Sensor.
Is the resistance between 300.0 and 1200.0 ohms?

without 45RFE

AUTO TRANS

Yes

→

Go To

→

Replace the Output Speed Sensor in accordance with the Service
Information.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

If there are no possible causes remaining, view repair.

without 45RFE

AUTO TRANS

Repair

Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform TRANSMISSION VERIFICATION TEST VER - 1.

105

DRIVEABILITY - DIESEL

P0720-LOW OUTPUT SPD SENSOR RPM, ABOVE 15 MPH —

Continued

TEST

ACTION

APPLICABILITY

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.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running and at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?

without 45RFE

AUTO TRANS

Yes

→

Repair as necessary
Perform TRANSMISSION VERIFICATION TEST VER - 1.

→

Test Complete.

106

DRIVEABILITY - DIESEL

P0720-LOW OUTPUT SPD SENSOR RPM, ABOVE 15 MPH —

Continued

Symptom List:

P0725-ENGINE SPEED SENSOR DYN. PLAUSIBILITY
P0725-ENGINE SPEED SENSOR STATIC PLAUSIBILITY

Test Note:

All symptoms listed above are diagnosed using the same tests.

The title for the tests will be P0725-ENGINE SPEED SENSOR
DYN. PLAUSIBILITY.

When Monitored and Set Condition:

P0725-ENGINE SPEED SENSOR DYN. PLAUSIBILITY

When Monitored:

The engine speed is above 790 RPM.

Set Condition:

The ECM detects a change in engine speed that has occurred more rapidly

than the engine is capable of changing speed.

P0725-ENGINE SPEED SENSOR STATIC PLAUSIBILITY

When Monitored:

With the engine speed above 700 RPM.

Set Condition:

The engine speed sensor signal indicates engine speed below 75 RPM and

the needle movement sensor signal (injector #1) indicates engine speed above 700 RPM.

POSSIBLE CAUSES

ENGINE CONTROL MODULE

INTERMITTENT CONDITION

ENGINE SPEED SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

ENGINE SPEED SENSOR CIRCUITS SHORTED TOGETHER

ENGINE SPEED SENSOR SIGNAL CIRCUIT OPEN

ENGINE SPEED SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE

ENGINE SPEED SENSOR

TEST

ACTION

APPLICABILITY

Attempt to start the engine.
Did the engine start?

All

Yes

→

Go To

→

Go To

107

DRIVEABILITY - DIESEL

Content .. 635 636 637 638 ..