Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit/System Description
The tire pressure monitor sensor, one in each wheel/tire assembly, sends sensor ID, tire temperature, tire rotation direction (N/A for TPMS manual learn), and tire pressure via radio frequency communication (RF).
The Remote Function Actuator (RFA) receives and translates the data contained in each sensors RF transmission and sends sensor ID, tire pressure and temperature data via the serial data communication link to BCM.
BCM holds the TPM application, calculates whether the tire pressure is OK or not, sets fault codes and sends data messages to DIC and IPC via serial communication data link requesting the appropriate tire pressure monitor indicator illumination and also to display the appropriate data message.
Diagnostic Aids
| • | If unsure about the condition, cycle the ignition and observe the tire pressure monitor indicator icon. If the tire pressure monitor indicator icon is continuously illuminated after the IPC bulb check is completed, a low tire pressure condition is present. Check the tires for damage or leaks and inflate to the tire placard specifications. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label. If the tire pressure monitor indicator icon flashes for 1 minute (60-90 seconds) after the IPC bulb check is completed and then remains illuminated, a tire pressure monitor system DTC is set. Perform the Diagnostic System Check - Vehicleto proceed with the proper diagnosis. |
| • | Temperature can greatly effect tire pressures. Low tire pressure on a cold morning may cause the tire pressure monitor indicator icon to turn ON. The air pressure in the tire increases as the ambient temperature rises or as the tire warms up while the vehicle is driven. The pressure may increase enough to exceed the predetermined low pressure threshold which will turn OFF the tire pressure monitor indicator icon. |
| • | Some aftermarket wheel valve stem holes are located further from the wheel rim than original equipment wheels. When using the TPM special tool to activate a sensor, ensure the tool antenna is no further than 15 cm (6 in) from the sensor and is aiming upward. |
| • | Aftermarket wheel value stem locations can cause a sensor to not function correctly. |
| • | A sensor may have been damaged due to a previous wheel/tire service or flat tire event. |
| • | The use of tire sealants can obstruct the sensor pressure sensing port and cause inaccurate tire pressure readings. If this condition is verified, remove the sealer from the tire and replace the sensor. Refer to Tire Pressure Indicator Sensor Replacement. |
| • | Occasionally sensor transmissions are not received by the RFA due to vehicle level RF interference from items such as but not limited to aftermarket ignition systems, DVD players, CB radios, or metallic type window tinting. |
| • | The sensor activation procedure may have to be repeated up to 3 times before determining a sensor is malfunctioning. In the event a particular sensor's information is displayed on the special tool upon activation but the horn does not chirp, it may be necessary to rotate the wheel valve stem to a different position due to the RF signal is being blocked by another component. |
| • | Occasionally sensors can become dislocated due to previous tire rotations where the sensor learn procedure was not performed or stray sensor transmissions have been received from other vehicles. Always learn the sensors to ensure the DTC set is for that actual physical corner of the vehicle. Refer to Tire Pressure Indicator Sensor Learn. |
Reference Information
Description and Operation
Tire Pressure Monitor Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Special Tools
CH-46079 Tire Pressure Monitor Diagnostic Tool
Circuit/System Verification
Note: : Low tire pressure in one or more tires is indicated by a continuously illuminated tire pressure monitor indicator icon after the IPC bulb check is completed. If equipped with a DIC, a check tire pressure type ("[LF/RF/RR/LR] tire pressure low") message will also be displayed. It is not necessary to perform the Learn procedure for a low tire condition.
When a TPM DTC is set, the tire pressure monitor indicator icon will flash for around 1 minute (60-90 seconds) after the IPC bulb check is completed and then remains illuminated. If equipped with a DIC, a service tire monitor type ("Service tire monitor system") message will also be displayed.- Verify all tires are inflated to the proper pressure within +10% using a known accurate hand held tire pressure gauge. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label. Set the correct tire pressure on cold ambient temperature (if possible) and do not set it when vehicle has just been moving a lot (-> hot tires -> influence tire pressure).
- Using the CH-46079 , activate each tire pressure sensor and record each sensor tire pressure reading. Check the tire pressures with a known accurate hand held tire pressure gauge. Verify that the pressure readings from the special tool do not differ more than 27.6 kPa (4 psi) from the actual tire pressure readings.
- Using a scan tool, enable the TPM learn mode. Use the CH-46079 in simulate mode to learn 4 simulated sensor transmissions into the BCM. Observe tire pressures in the scan tool data display. Verify the simulated tire pressures do not differ more than +/-27.6 kPa (4 psi) of the scan tool reading (compared with pressure values in DIC display).
- Using a scan tool, perform the instrument panel special functions Lamp Test. Command the instrument panel warning lamps ON and OFF. Verify the tire pressure monitor indicator icon turns ON and OFF.
- Ignition ON, use the scan tool to setup the Tire Type/Pressure Selection in the BCM Module Setup menu. Refer to the Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label. Drive the vehicle over 20 km/h (15 mph) for more than 2 minutes (maximum 10 minutes cumulative driving). Verify the tire pressure monitor indicator icon goes OFF.
⇒ If not within the specified range, adjust all tire pressures to specification and drive the vehicle over 20 km/h (15 mph) for more than 2 minutes (maximum 10 minutes cumulative driving). Verify the tire pressure monitor indicator icon is OFF.
⇒ If not within the specified range, replace the appropriate tire pressure sensor.
⇒ If not within the specified range, replace the BCM.
⇒ If the tire pressure monitor icon does not turn ON and OFF, replace the IPC.
⇒ If the tire pressure monitor indicator icon is ON, replace the BCM.
Repair Instructions
Perform the Diagnostic Repair Verificationafter completing the diagnostic procedure.
| • | Control Module References for IPC, BCM, ALM, or RFA replacement, setup, and programming |
