Tire Monitoring System: Description and Operation
Principles of Operation
Special Tool(s)
The Tire Pressure Monitoring System (TPMS) monitors the air pressure of all four regular road tires. The wheel-mounted tire pressure sensors transmit via Radio Frequency (RF) signals, to the TPMS module (integral to the Vehicle Security Module (VSM)), 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 (integral to VSM), compares each tire pressure sensor transmission against a low-pressure limit. If the module determines that the tire pressure has fallen below this limit, the module communicates this on the Controller Area Network (CAN) to the instrument cluster, illuminates the TPMS indicator and displays the appropriate message center message.
The system is not affected by wheel and tire rotation.
Ambient Temperature Change and Tire Pressure
CAUTION: Do not inflate tire higher than maximum pressure stamped on tire sidewall.
As the ambient temperature decreases by 12°C (10°F), tire pressure decreases 7 kPa (1 psi). Adjust the tire pressure by 7 kPa (1 psi) for each 12°C (10°F) ambient temperature drop as necessary to keep the tire at the specified vehicle placard pressure.
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. Symptom Related Diagnostic Procedures
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.
TPMS Indicator Illuminates Continuously
The TPMS indicator remains on continuously for the following condition:
1. 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 before carrying out any diagnosis
Low Tire Pressure - The TPMS indicator is illuminated solid and the message center displays LOW 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.
Refer to Information Bus for diagnosis of the CAN bus.
TPMS indicator flashes (flashes for 20 seconds after prove-out. The TPMS indicator flashes for the following three reasons:
1 No Communication with the TPMS Module (integral to VSM) The TPMS indicator is illuminated when the instrument cluster (IC) has received no signals from the VSM for more than 5 seconds. If equipped, the message center displays TIRE PRESSURE MONITOR FAULT. GO to Symptom Chart. Symptom Related Diagnostic Procedures
2 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. Symptom Related Diagnostic Procedures
3 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