Jeep Liberty KJ. Manual - part 1257

Theory of Operation

The tire pressure sensor actively monitors the air pressure and air temperature inside the tire, the sensor internal
battery status, and the radial acceleration of the wheel. Each sensor has a unique ID code. The sensor transmits
the data at regular intervals via an encoded signal to a receiver circuit located in the Wireless Control Module
(SKREEM).

•

When Monitored:
With vehicle speed greater than 15 m.p.h. (24 km/h).

•

Set Condition:
The WCM (SKREEM) will monitor the signals from the four active road tire sensors. A loss of signal error is
detected when eight consecutive blocks of data are not received or cannot be accurately decoded. An internal
sensor hardware error condition will be set when an error in the accelerometer, pressure sensor, or tempera-
ture sensor is detected.

Possible Causes

INTERMITTENT TIRE PRESSURE SENSOR INTERNAL DTC

TIRE PRESSURE SENSOR

WIRELESS CONTROL MODULE (SKREEM)

Diagnostic Test

DTC STATUS IS ACTIVE

NOTE: If the incorrect Placard Values were programmed into the WCM/SKREEM, a DTC could be set. Before
continuing with any TPM diagnostic test, using the scan tool, check that the correct Placard Values have
been programmed in to the module.

NOTE:
If the following conditions are present:
– Low Tire Pressure DTC (Stored)
– Tire Pressure Sensor Internal DTC (Active)
– Spare Tire is not equipped with a Tire Pressure Sensor
– Spare Tire is currently on the vehicle
Repair the tire and place it back on the vehicle.
Test drive the vehicle.
If the DTC(s) reset continue with the diagnostic procedure.
Turn the ignition on.

With the scan tool, select View DTCs in the Wireless Control Module (SKREEM).

Is the DTC status Active at this time?

Yes

>> Go to 2

>> Go to 4

TIRE PRESSURE SENSOR

NOTE:
When working with vehicles equipped with the base tire pressure monitoring system the correct tire that set
the fault must be identified. Following the below procedure will help in identifying the correct tire.
1. Set all tire pressures to the recommended specifications and recheck for fault/alert.
2. Turn the ignition on.
3. Starting with the left front wheel, deflate the tire to 20 PSI and wait 2 minutes. The fault will set once the
pressure has reached 20 PSI within the 2 minute time frame.
4. If the TPM fault was detected and not associated to this Sensor/Transmitter, repeat the process until the
faulty Sensor/Transmitter has been identified.Once a fault/alert has set, it will establish the location of the
tire pressure sensors/transmitter. Repeat steps until the applicable Tire Pressure Sensor/Transmitter has
been located.
Turn the ignition off.

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TIRES/WHEELS - ELECTRICAL DIAGNOSIS

Replace the Tire Pressure Sensor in accordance with the Service Information.

With the scan tool, clear DTCs in the Wireless Control Module (SKREEM).

Test Drive the vehicle for a minimum of 10 minutes with vehicle speed greater than 15 m.p.h.

With the scan tool, select View DTCs in the Wireless Control Module (SKREEM).

Does the DTC reset or is the status Active for this DTC?

Yes

>> Go to 3

>> Test Complete.

WIRELESS CONTROL MODULE (SKREEM)

View repair.

Repair

Replace the Wireless Control Module (SKREEM) in accordance with the Service Information.

INTERMITTENT TIRE PRESSURE SENSOR DTC

The conditions necessary to set this DTC are not present at this time.

Refer to any Technical Service Bulletins that may apply to this condition.

With the scan tool, clear DTCs in the Wireless Control Module (SKREEM).

Test Drive the vehicle for a minimum of 10 minutes with vehicle speed greater than 15 m.p.h.

With the scan tool, select View DTCs in the Wireless Control Module (SKREEM).

Does the DTC reset or is the status Active for this DTC?

Yes

>> Return to the beginning of this test and perform the diagnostic procedure as necessary.

>> Test complete.

TIRES/WHEELS - ELECTRICAL DIAGNOSIS

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C1506–LEFT FRONT TIRE PRESSURE TRIGGER MODULE PERFORMANCE

For a complete wiring diagram Refer to Section 8W

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TIRES/WHEELS - ELECTRICAL DIAGNOSIS

Theory of Operation

The Tire Pressure Trigger Module is used to automatically learn the location of each wheel sensor on the vehicle.
The module is controlled and activated in sequence by the Wireless Control Module (SKREEM) over a LIN bus.
When activated, the module will generate a 125 KHz signal of sufficient field strength to trigger the tire pressure
sensor and force a RF transmission from the sensor.

•

When Monitored:
Continuously.

•

Set Condition:
The WCM (SKREEM) will monitor the messages from each Tire Pressure Trigger Module over the LIN bus. If
any of the messages are not received, or are received other than as expected, a DTC will set. When the
condition is corrected, or is no longer detected, as acknowledged via a LIN bus message, the WCM will reset
the appropriate trigger module fault status.

Possible Causes

INTERMITTENT TIRE PRESSURE TRIGGER MODULE PERFORMANCE DTC

(D508) COM - LIN TIRE PRESSURE MONITOR LAN CIRCUIT SHORT TO VOLTAGE

(D508) COM - LIN TIRE PRESSURE MONITOR LAN CIRCUIT SHORT TO GROUND

(D508) COM - LIN TIRE PRESSURE MONITOR LAN CIRCUIT OPEN OR HIGH RESISTANCE

(F924) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT OPEN OR HIGH RESISTANCE

(Z924) GROUND CIRCUIT(S) OPEN OR HIGH RESISTANCE

TIRE PRESSURE TRIGGER MODULE

WIRELESS CONTROL MODULE (SKREEM)

Diagnostic Test

DTC STATUS IS ACTIVE

With the scan tool, select View DTCs in the Wireless Control Module (SKREEM).

Is the DTC status Active at this time?

Yes

>> Go to 2

>> Go to 9

(F924) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT OPEN OR HIGH RESISTANCE

Turn the ignition off.

Disconnect the Tire Pressure Transponder harness connector.

Disconnect the Sentry Key Remote Entry Module harness connector.

Turn the ignition on.

Using a 12–volt test light connect to ground, check the (F924) Fused
Ignition Switch Output (Run) circuit.

TIRES/WHEELS - ELECTRICAL DIAGNOSIS

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