C0077 Low Tire Pressure

C0077 Low Tire Pressure - A low pressure condition will exist when the tire pressure falls below or is equal to the low pressure threshold value as specified for the vehicle.

Possible causes:

• Intermittent performance DTC.
• Incorrect tire pressure.
• Tire Pressure Monitoring (TPM) sensor.
• Wireless Control Module (WCM).

Diagnose DTC C0077 Low Tire Pressure

Step 1. DTC status is active

The TPM transponders are commonly known as trigger modules.

If any the following conditions are present repair them first before continuing with this diagnostic procedure.

• Low tire pressure DTCs.
• Tire pressure sensor internal fault.
• Spare tire is not equipped with a tire pressure sensor and is currently on the vehicle.

With the scan tool, erase DTCs. Test drive the vehicle at speeds greater than 24 km/h (15 mph) for 10 minutes in order to receive TPM sensor data. Ignition on, engine not running, with the scan tool, read DTCs?

Is the DTC status active at this time?

YES, go to step 2.

NO, go to step 8.

Step 2. Low tire pressure

Some vehicles will not receive TPM sensor data when the vehicle is stationary. The vehicle will need to be driven at speeds greater than 24 km/h (15 mph) for about a minute in order to receive TPM sensor data.

Correct all tire pressures to the recommended cold inflation tire pressure specifications and wait two miniutes for the system to update. With the scan tool, clear and read DTCs.

Does the DTC reset or is the status active for this DTC?

YES, go to step 3.

NO, the conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.

Step 3. Tire pressure sensor

The following tests are used to locate the TPM sensor that is setting the low pressure fault. If the tires have been rotated, the TPM sensor is no longer is sequence from the factory. Faults are linked to the sensor IDs. You must locate the correct TPM sensor that set the fault before.

Before continuing with any TPM diagnostic test, using the scan tool and read first set of the tire placard pressure front and tire placard pressure rear under data display in the WCM. (under the left rear transponder status) confirm that the values match the tire inflation presure (placard) label located on the driver side B-pilar. If the incorrect placard values have benn programmed in the WCM. Go to update pressure threshold under miscellaneous functions for the WCM and follow the precedure. If the vehicle is equipped with WCM module, go into the front control module (FCM), select data display and read ''tire placard pressure front'' and ''tire placard pressure rear'' to confirm the values were programmed correctly. If the placard values are incorrect in the FCM, select front control module (FCM) then under ''miscellaneous'' select ''update pressure threshold'' and enter the placard pressure value as seen on the tire inflation pressure (placard) label.

With the scan tool, select view data display in the WCM and find the compensated tire pressure values located under each of the sensor identification locations.

Are any of the compensated tire pressure values are below the placard value?

YES, replace the tire pressure sensor.

NO, go to step 4.

Step 4. TPM/RKE Analyzer

Is there a TPM/RKE analyzer 9936 available?

YES, go to step 5.

NO, go to step 7.

Step 5. Tire pressure monitoring (TPM) sensor non-responsive

With the TPM/RKE analyzer 9936, check to see if the any of the TPM sensors do not respond after repeated attempts or display the following:

• ''Damaged accel''
• ''Damaged temp''
• ''Damaged press''

Are any of the TPM sensors not responding or displaying the information listed above?

YES, replace the tire pressure minitoring (TPM) sensor.

NO, go to step 6.

Step 6. Tire pressure sensor internal fault set using TPM/RKE analyzer

The following procedure is used to locate the tire pressure sensor/transmitter that is setting the sensor internal fault. If the tires have been rotated, the tire pressure sensor/transmitter is no longer in sequence from the factory. Faults are linked to the sensor IDs. You must locate the correct TPM sensor that set the fault before continuing. Use the following method below at every tire location.

If the sensor IDs fo not match, it may be necessary to move the vehicle to a location away from other TPM sensors and repeat this step.

With the scan tool, select data display for the WCM. Check to see if the sensor IDs match what is programmed into the WCM.

Has the tire pressure sensor been located?

YES, replace the tire pressure monitoring (TPM) sensor.

NO, replace the Wireless Control Module (WCM). Perform the WCM system verification.

Step 7. Tire pressure internal fault set
Some vehicles will not receive TPM sensor data when the vehicle is stationary. The vehicle may need to be driven at speeds greater than 24 km/h (15 mph) for about a minute in order to receive TPM sensor data.

Starting with the left fron wheel, deflate the tire to 20 psi, wait two minutes, and check the scan tool for changes to any compensated tire pressure values. Look for a tire location whose sensor ID that is not responding. Repeat this test on each wheel on the vehicle until the sensor in question has been identified.

Has the tire pressure sensor been located?

YES, replace the Tire Pressure Monitoring (TPM).
NO, replace the Wireless Control Module (WCM), Perform the WCM system verification.

Step 8. Intermittent tire pressure sensor DTC
The conditions necessary to set this DTC are not present at this time. Perform any technical service bulletins that may apply to this condition. With the scan tool, clear DTCs. Test drive the vehicle for a minimum with vehicle speed greater than 24 km/h (15 mph). With the scan tool, read DTCs.

Does the DTC reset or is the status active for this DTC?

YES, replace the Wireless Control Module (WCM). Perform the WCM system verification.

NO, test complete.

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