DIAGNOSIS AND TESTING

C0077- LOW TIRE PRESSURE

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

The Tire Pressure Monitoring System (TPMS) will warn the driver of a low tire pressure based on the vehicle recommended cold placard pressure. The tire pressure will vary with temperature by about 1 psi (6.9 kPa) for every 12°F (6.5°C). This means that when the outside temperature decreases, the tire pressure will decrease. Tire pressure should always be set based on cold inflation tire pressure. This is defined as the tire pressure after a vehicle has not been driven for more than 3 hours - and in outside ambient temperature. . The tire pressure will also increase as the vehicle is driven - this is normal and there should be no adjustment for this increased pressure. The TPM System will warn the driver of a low tire pressure if the tire pressure falls below the low pressure warning threshold for any reason, including low temperature effects. The TPM System will continue to warn the driver of low tire pressure as long as the condition exists, and will not turn off until the tire pressure is at or above recommended cold placard pressure. Once the low tire pressure warning has been illuminated, the tire pressure must be increased to the recommended cold placard pressure in order for the TPM warning lamp to be turned off. The system will automatically update and the TPM warning lamp will extinguish once the updated tire pressures have been received. The vehicle may need to be driven for up to 10 minutes above 15 mph (25 kph) to receive this information. Seasonal temperature changes will affect tire pressure, and the TPM system will monitor the actual tire pressure in the tire. For example, your vehicle may have a recommended cold (parked for more than 3 hours) placard of 30 (207 kPa). If the ambient temperature is 68°F (20°C) and the measured tire pressure is 27 psi (186 kPa), a temperature drop to 20°F (-7°C) will decrease the tire pressure to approximately 23 psi (157 kPa). This tire pressure is sufficiently low enough to turn ON the TPM lamp. Driving the vehicle may cause the tire pressure to rise to approximately 27 psi (186 kPa), but the TPM lamp will still be ON. In this situation, the TPM lamp will turn OFF only after the tires have been inflated to the vehicle’s recommended cold placard pressure value.

• When Monitored:

  Continuously.

• Set Condition:

  A low pressure condition will exist when the tire pressure falls below or is equal to the low pressure threshold value as specified for the vehicle.

• Go to 2

• Go to 5

• Go to 3

• Update placard pressure values in the WCM.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING - STANDARD PROCEDURE)

• Go to 4

• Fill all tires to placard pressure specifications.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING - STANDARD PROCEDURE)

• Replace the Wireless Control Module (SKREEM) in accordance with the Service Information.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS - DIAGNOSIS AND TESTING)

• Test Complete.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING - STANDARD PROCEDURE)

• Repair as necessary.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS - DIAGNOSIS AND TESTING)

• Test complete.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING - STANDARD PROCEDURE)

C1501-TIRE PRESSURE SENSOR 1 INTERNAL

For a complete wiring diagram Refer to Section 8W

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 MPH (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 within a maximum period of 10 minutes. An internal sensor hardware error condition will be set when an error in the accelerometer, pressure sensor, or temperature sensor is detected.

• Go to 2

• Go to 4

• Go to 3

• Test Complete.
• Perform TPM VERIFICATION TEST. (Refer to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING - STANDARD PROCEDURE)