Low Tire Pressure Indicator Inoperative

Low Tire Pressure Indicator Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Circuit/System Description

The lift gate module (LGM) receives a radio frequency (RF) transmission from each tire pressure sensor. Each sensor RF transmission contains its own unique identification (ID) code that must be learned into the LGM memory. Once all 4 IDs have been learned and vehicle speed is greater than 40 km/h (25 mph), the LGM continuously compares IDs in received transmission to its learned IDs to determine if all 4 sensors are present. If the LGM detects a low tire pressure condition or a malfunction in the system, it will send a serial data message to the instrument panel cluster (IPC) requesting tire pressure monitor indicator illumination and to display a data message on the driver information center (DIC), if equipped.

Diagnostic Aids

* 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 (Tire Pressure Indicator Sensor Replacement).
* Occasionally sensor transmissions are not received by the LGM 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 mislocated 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 Sensor Learn (Service and Repair).

Reference Information
Description and Operation

Tire Pressure Monitor Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Control Module References) for Scan Tool Information
Special Tools

J-46079 Tire Pressure Monitor Diagnostic Tool

Circuit/System Verification

1. Ignition ON, with the scan tool, setup the Tire Type and Pressure Selection information in the LGM. Refer to the Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label (Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label).
2. With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel lamps ON. Verify tire pressure monitor indicator icon turns ON.

• If the icon does not turn ON, replace the IPC.

3. Using the tire pressure monitor (TPM) special tool to observe the tire pressure of the suspected faulty sensor. Check the air pressure with a known accurate tire pressure gage. Compare the pressure reading to the display on the TPM special tool. Verify the pressure readings from special tool do not differ 27.6 kPa (4 psi) or more than actual tire pressure.

• If not within the specified range, replace the suspect tire pressure sensor.

4. With the scan tool, observe tire pressures in the scan tool data display. Verify pressure readings from special tool do not differ 27.6 kPa (4 psi) or more than scan tool data display.

• If not within the specified range, replace the LGM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Tire Pressure Indicator Sensor Replacement (Tire Pressure Indicator Sensor Replacement)
* Tire Pressure Sensor Learn (Service and Repair)
* Control Module References (Control Module References) for IPC and LGM replacement, setup, and programming