Circuit Description
The tire pressure monitor (TPM) system uses the electronic brake control module (EBCM), and The ABS wheel speed sensor inputs to monitor tire pressure. The EBCM contains software to calculate relative tire pressure differences. The EBCM monitors the ABS wheel speed sensor inputs, which will all be the same as the learned calibration if the tire pressures stay the same. If the pressure increases or decreases in one tire so too will that tires circumference and radius, which causes that wheel speed sensor input to change. The EBCM recognizes this change in wheel speed as a tire pressure condition.
Conditions for Running the DTC
| • | No ABS or TCS malfunctions present. |
| • | The calibration process is at least partially complete. |
| • | The vehicle speed is between 24-145 km/h (15-90 mph). |
Conditions for Setting the DTC
| • | The EBCM detects a tire pressure difference in 1 tire of 69 kPa (10 psi) higher or lower than the other 3. |
| • | A loss of, or low system battery voltage. |
Actions Taken When the DTC Sets
| • | A DTC C0774 is stored in memory. |
| • | The DIC displays the CHECK TIRE PRESSURE warning message. |
| • | The system is disabled. |
Conditions for Clearing the DTC
| • | A current DTC will clear when the TPM system is reset. |
| • | A history DTC will clear after 100 consecutive malfunction free ignition cycles from when the TPM system has been reset. |
| • | Using the scan tool. |
Diagnostic Aids
Any of the following conditions can also cause this DTC to set.
| • | The tire pressures have been adjusted without resetting the TPM system. |
| • | The tires have been rotated or replaced without resetting the TPM system. |
| • | The tires are different in size than the original equipment manufacturers. |
| • | Rough or slippery road conditions such as dirt, gravel, wet, snow, or ice. |
| • | Tires out of balance. |
| • | A suspension out of alignment. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Inspect the tire pressures and adjust to the recommended kPa/psi if needed. Refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication, or to Tire Placard in General Information. Did incorrect tire pressure cause the DTC to set? | Go to Step 3 | Go to Diagnostic Aids | |
3 | Reset the TPM system. Refer to Tire Pressure Monitor Procedure . Did you complete the repair? | Go to Step 4 | -- |
4 |
Does the DTC reset? | Go to Step 2 | System OK |
