C0778
DTC C0775, C0776, C0777, or C0778
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using the 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.
DTC Descriptors
DTC C0775
- Air Pressure Warning
DTC C0776
- Air Pressure Warning
DTC C0777
- Air Pressure Warning
DTC C0778
- Air Pressure Warning
Circuit/System Description
The tire pressure monitor (TPM) system has a radio frequency (RF) transmitting pressure sensor in each wheel/tire assembly. As vehicle speed increases, centrifugal force closes the sensors internal roll switch, which puts the sensor into Drive mode. The tire pressure module receives and translates the data contained in the tire pressure sensor RF transmissions into sensor presence, sensor mode, and tire pressure. The tire pressure module receives vehicle speed information from the transmission control module (TCM). Once a vehicle speed signal of greater than 32km/h (20 mph) is received, the tire pressure module waits for the sensors to go into Drive mode. If the tire pressure is below or above the predetermined threshold specification or if there is a malfunction in the tire pressure monitor system, the tire pressure module will illuminate the low tire pressure indicator icon on the instrument panel cluster (IPC).
Conditions for Running the DTC
Vehicle speed is above 32 km/h (20 mph).
Conditions for Setting the DTC
* The tire inflation pressure is below the predetermined threshold.
* A tire pressure sensor is transmitting an inaccurate pressure reading.
Action Taken When the DTC Sets
The instrument panel cluster (IPC) tire pressure indicator warning lamp icon will remain illuminated.
Conditions for Clearing the DTC
* The conditions for setting the DTC are no longer present.
* The DTC can be cleared with the scan tool.
Reference Information
Schematic Reference
Tire Pressure Monitoring System Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
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
Tire Pressure Indicator Receiver Scan Tool Information (Scan Tool Testing and Procedures)
Special Tools
J-46079 Tire Pressure Monitor Diagnostic Tool
Circuit/System Verification
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. 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.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Tire Pressure Indicator Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for tire pressure module replacement, programming, and setup.