Circuit Description
The tire pressure monitor (TPM) system uses the electronic brake control module (EBCM), and the antilock brake system (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 tire's 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1245 Tire Pressure Low
Conditions for Running the DTC
| • | No ABS or traction control system (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 one tire of 69 kPa (10 psi) higher or lower than the other 3. |
| • | Loss of, or low system battery voltage |
Actions Taken When the DTC Sets
| • | DTC C1245 is stored in memory. |
| • | The systems monitor displays the TIRE PRESS indicator, or the driver information center (DIC) displays the CHECK TIRE PRESSURE warning message, if equipped. |
| • | The TPM system is disabled. |
Conditions for Clearing the DTC
| • | A current DTC will clear when the TPM system has been reset. |
| • | A history DTC will clear after 100 consecutive malfunction-free ignition cycles and the TPM system has been reset. |
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. |
| • | Rough or slippery road conditions such as dirt, gravel, wet, snow, or ice |
| • | The tires are out of balance. |
| • | The suspension is out of alignment. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Tire Pressure Monitoring System Schematics | |||
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 Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label in General Information. Did incorrect tire pressure cause the DTC to set? | Go to Step 3 | Go to Diagnostic Aids | |
3 | Reset the tire pressure monitor (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 | -- |
