GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2001 🢒 Regal (China) 🢒 DTC 🢒 DTC C1245

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 pressure stay the same. If the pressure increases or decreases in one tire so to 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.

Conditions for Running the DTC
    • No ABS or TCS malfunctions present.
    • The calibration process is 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 three.
    • Loss of, or low system battery voltage.

Actions Taken When the DTC Sets
    • A DTC C1245 is stored in memory.
    • The systems monitor displays the TIRE PRESS indicator, or the DIC displays the CHECK TIRE PRESSURE warning message.
    • The TPM system is disabled.

Conditions for Clearing the DTC
    • A current DTC will clear when the malfunction is no longer present and the calibration procedure is initialized.
    • A history DTC will clear after 100 consecutive ignition cycles with no malfunction present and the calibration procedure is initialized.
    • Using the scan tool

Diagnostic Aids

Any of the following conditions can also cause this DTC to set.

    • The tire pressures have been altered without calibrating the TPM system.
    • The tires have been rotated or changed without calibrating the TPM system.
    • The tires are different in size than the original equipment manufacturer's.
    • Rough or slippery road conditions (dirt, gravel, wet, snow, or ice).
    • The tires are out of balance.
    • A suspension out of alignment.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step inspects the tires for proper tire pressures.

Step

Action

Yes

No

Schematic Reference: Tire Pressure Monitoring System Schematics

1

Did you perform the Tire Pressure Monitor Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Tire Pressure Monitoring

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC Information for DTC C1245 in the DRP/ABS/TCS/TIM/VSES (if equipped) Diagnostic Trouble Codes (DTCs).

Does the scan tool indicate that DTC C1245 is current?

Go to Step 3

Go to Diagnostic Aids

3

Since some occurrences of this DTC are caused by driving conditions, or different tire size, review the TPM system with the customer to verify the conditions under which the DTC set.

Did driving conditions, or tire size cause this DTC to set?

Go to Step 5

Go to Step 4

4
  1. Calibrate the TPM system. Refer to Tire Pressure Monitor Procedure .
  2. Use the scan tool in order to clear the DTCs.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset as a current DTC?

Go to Step 5

System OK

5

Inspect the tire pressures and set to manufacturers specification if needed. Calibrate the TPM system if tire pressures were adjusted. Refer to Tire Pressure Monitor Procedure .

Did you complete the repair?

System OK

--