Low Tire Pressure Indicator Malfunction

Low Tire Pressure Indicator Malfunction

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 module receives a radio frequency (RF) transmission from each tire pressure sensor. Each sensor has its own unique identification (ID) code, which it transmits as part of each RF message, that must be learned into the module memory. Once all 4 IDs have been learned and vehicle speed is greater than 32 km/h (20 mph), the module continuously compares IDs in received transmission to its learned IDs to determine if all 4 sensors are present. If the module detects a low tire pressure condition or a malfunction in the system, it will ground the control circuit for the instrument panel cluster (IPC) low tire pressure indicator icon illuminating the icon.

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 specification. Refer to the placard specification label. If the tire pressure monitor indicator icon flashes for 1 minute after the IPC bulb check is completed and then remains illuminated, a tire pressure monitor system DTC is set. Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) to 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 other than GM approved 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 tire pressure 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 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 Monitor System Configuration (Programming and Relearning).

Reference Information
Schematic Reference

Tire Pressure Monitoring System Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
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
Special Tools

J-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 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 approximately 75 seconds after the IPC bulb check is completed. If equipped with a DIC, a service tire monitor type message will also be displayed.

1. Verify all tires are inflated to the proper pressure ±10%. Refer to the tire placard label.

• If not within the specified range, adjust all tire pressures to specification and drive the vehicle over 32 km/h (20 mph) for greater than 2 minutes. Verify the tire pressure monitor indicator icon is OFF.

2. Using the J-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.

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

3. At 32 km/h (20 mph), use a scan tool to verify a vehicle speed data parameter is displayed in the tire pressure monitor data list.

• If no vehicle speed displayed, test the tire pressure module vehicle speed signal circuit for an open/high resistance, short to ground, or short to voltage. If the circuit tests normal, replace the tire pressure module.

4. Ignition OFF, disconnect the tire pressure module.
5. Test for less than 5 ohm at the tire pressure module connector ground circuit terminal 11.

• If greater than the specified range, test the ground circuit for an open/high resistance.

6. Ignition ON, connect a test lamp between the following tire pressure module connector supply voltage circuit terminals and ground.

* Terminal 1
* Terminal 8

• If the test lamp does not illuminate, test the appropriate supply voltage circuit for an open/high resistance. If the fuse is open, test the circuit for a short to ground. If all circuits test normal, replace the tire pressure module.

7. Apply the parking brake.
8. Test for less than 5 ohm at the tire pressure module connector park brake signal circuit terminal 4.

• If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the tire pressure module.

9. Verify the horn sounds by pressing the steering wheel horn pad. If the horn does not sound, refer to Symptoms - Vehicle (Symptoms - Vehicle).
10. Momentarily connect a 3 A fused jumper between the tire pressure module connector horn control circuit terminal 9 and ground. Verify the horn sounds when the fused jumper is connected.

• If the horn does not sound, test the control circuit for an open/high resistance. If the circuit tests normal, replace the tire pressure module.

11. Ignition ON, engine running, test for B+ at the tire pressure module connector generator output signal circuit terminal 7.

• If less than the specified range, test the signal circuit for an open/high resistance or short to voltage. If the circuit tests normal, replace the tire pressure module.

12. Using a scan tool, enable the TPM learn mode. Use the J-46079 in simulate mode to learn 4 simulated sensor transmissions into the tire pressure module. 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.

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

13. Using a scan tool, perform the instrument panel special functions Lamp Test. Command the instrument panel warning lamps ON and OFF.

• If the tire pressure monitor icon does not turn ON and OFF, replace the bulb or IPC.
• If the tire pressure monitor icon does turn ON and OFF, test the tire pressure module warning lamp control circuit for an open/high resistance, short to ground, or short to voltage. If all circuits tests normal, replace the tire pressure module.

Repair Instructions

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

* Tire Pressure Indicator Sensor Replacement (Service and Repair)
* Low Tire Pressure Indicator Module Replacement (Service and Repair)
* Instrument Cluster Bulb Replacement (Notchback) (Service and Repair)
* Instrument Cluster Replacement (Service and Repair)
* Tire Pressure Monitor System Configuration (Programming and Relearning)