Tire Monitoring System: Description and Operation

Principles of Operation
The Tire Pressure Monitoring System (TPMS) monitors the air pressure of all four regular road tires. The tire-mounted pressure sensors transmit via Radio Frequency (RF) signals to the TPMS module, using the valve stem as an antenna. These transmissions are sent approximately every 60 seconds when the vehicle speed exceeds 32 km/h (20 mph). The TPMS module compares each tire pressure sensor transmission against a set of low-pressure limits. If the TPMS module determines that the tire pressure has fallen below these limits, the TPMS module communicates this on the CAN network to the vehicle's instrument cluster which then illuminates the TPMS indicator and displays the appropriate message center message (if equipped).

The system is not affected by wheel and tire rotation.

TPMS Indicator and Vehicle Message Center Messages
The TPMS indicator and vehicle message center (if equipped) sometimes displays faults that cannot be resolved by the customer. Treat these messages as TPMS faults that must be serviced. GO to Symptom Chart for the TPMS indicator operation and message center messages.

TPMS Indicator Illuminates Continuously
The TPMS indicator remains on continuously for the three following conditions:

CAUTION: Place the air chuck straight on the valve stem to inflate the tire. Do not cock the air chuck during the inflation cycle. Doing so can damage the valve stem and cause air leaks.







CAUTION: Ford recommends using a round head air chuck on tire pressure sensors; it is not recommended to use air chucks with long shanks. Doing so can cause tire pressure sensor valve stem damage and loss of tire pressure.

1. Low Tire Pressure-The TPMS indicator is illuminated solid and message center displays CHECK TIRE PRESSURE (if equipped). This is displayed when any of the tire pressures are low. Tire pressure must be adjusted to the recommended cold placard pressure. ADJUST the air pressure in tires.

2. Very Low Tire Pressure-The TPMS indicator is illuminated solid and the message center displays WARNING-TIRE VERY LOW (if equipped). This is displayed when one or more tires have very low pressure. When this warning message is displayed, a warning chime sounds reminding you to stop the vehicle as soon as safely possible and check the tires for correct pressure, and for leaks or damage. Tire pressure must be adjusted to the recommended cold placard pressure. ADJUST the air pressure in tires.

3. No Communication with the TPMS Module- The TPMS indicator is illuminated when the Instrument Cluster (IC) has received no signals from the TPMS module for more than 5 seconds. If equipped, the message center displays TIRE PRESSURE MONITOR FAULT. GO to Symptom Chart.

TPMS Indicator Flashes (flashes for 20 seconds at prove-out and every hour of operation)
The TPMS indicator flashes for the following reasons:

NOTE: If the spare tire is in use, the damaged road tire must be repaired and installed on the vehicle to restore complete TPMS functionality.

- Tire Pressure Sensor Fault-If equipped, the message center will display TIRE PRESSURE SENSOR FAULT when a tire pressure sensor is malfunctioning. GO to Symptom Chart.
- Tire Pressure Monitor Fault-If equipped, the message center will display TIRE PRESSURE MONITOR FAULT when the tire pressure monitoring system is malfunctioning. GO to Symptom Chart.
Symptom Related Diagnostic Procedures

Symptom Chart
Failure of a tire pressure monitor system component may not cause the message center to display a system fault message or a DTC to be stored. The Symptom Chart is a starting point to begin diagnosis of these concerns.