Low Tire Pressure Indicator Always On
Low Tire Pressure Indicator Always On
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Circuit/System Description
The tire pressure monitor (TPM) system has a radio frequency (RF) transmitting pressure sensor in each wheel/tire assembly. The module receives and translates the data contained in the tire pressure sensor RF transmissions into sensor presence, sensor mode, and tire pressure.
The receiver module 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 module memory. Once all 4 IDs have been learned, the module continuously compares IDs received in transmission to its learned IDs to determine if all 4 sensors are present.
If the control module detects a low tire pressure condition or a malfunction in the system, it will illuminate the tire pressure monitor indicator.
Diagnostic Aids
* 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 (Service and Repair)
* Occasionally sensor transmissions are not received by the control module 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 before determining a sensor is malfunctioning. In the event a particular sensor's information is displayed on the special tool, 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.
Reference Information
Description and Operation
Tire Pressure Monitor Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Important: When a TPM DTC is set, the tire pressure monitor indicator icon will flash for 1 minute after the IPC bulb check is completed and then remains illuminated.
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.
Circuit/System Verification
1. Inflate all tires to the proper pressure and drive the vehicle over 40 km/h (25 MPH) for over 2 minutes.
2. Using a scan tool, select instrument panel special functions Lamp Test. Command the instrument panel warning lamps OFF. Verify the tire pressure monitor indicator icon turns OFF.
• If the tire pressure monitor icon does not turn OFF, replace the IPC.
3. Disconnect the harness connector at the Tire Pressure Control Module.
4. Disconnect the harness connector at the IPC.
5. Test for less than 1 ohm of resistance between the warning light control circuit terminal 6 and terminal 1.
• If greater than the specified value, test the warning light control circuit for an open/high resistance.
6. Test for infinite resistance between the warning light control circuit terminal 6 and ground.
• If less than the specified value, test the warning light control circuit for a short to ground. If circuit tests normal, replace the tire pressure control module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Tire Pressure Indicator Sensor Replacement (Service and Repair)
* Tire Pressure Sensor Learn (Programming and Relearning)
* Control Module References (Programming and Relearning) for IPC or module replacement, programming, and setup.