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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Vibe - FWD 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC C2121-C2124

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

DTC Descriptors

DTC C2121: Tire Pressure Sensor 1 Signal Missing - Main Set

DTC C2122: Tire Pressure Sensor 2 Signal Missing - Main Set

DTC C2123: Tire Pressure Sensor 3 Signal Missing - Main Set

DTC C2124: Tire Pressure Sensor 4 Signal Missing - Main Set

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.

Conditions for Running the DTC

Vehicle speed is 5 mph or greater for 20 minutes.

Conditions for Setting the DTC

No signals are received after the vehicle is driven 20 minutes or more.

Action Taken When the DTC Sets

The Tire Pressure Warning Light is illuminated.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Diagnostic Aids
    • The sensor activation procedure may have to be repeated up to 3 times before determining a sensor is malfunctioning.
    • Occasionally sensor transmissions are not received by the tire pressure receiver module due to vehicle level RF interference.

Reference Information

Description and Operation

Tire Pressure Monitor Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing
  1. With the scan tool, verify that DTC C2173 is not set.
    2. ⇒If DTC C2173 is set, refer to DTC C2173 .
  2. With the scan tool, locate and record tire pressure sensors ID and locations.
    3. 2.1. Rapidly reduce the tire pressure for each wheel at least 6 psi within 30 seconds. It may take up to 3 minutes for the display to change.
    2.2. Record the sensor ID and location.
    ⇒If any of the parameters listed above do not change or are not displayed for one sensor, replace the suspect tire pressure sensor.
  3. Disconnect the harness connector at the tire pressure control module.
  4. Disconnect the harness connector at the tire pressure receiver module.
  5. Test for less than 1 ohm between the 5-volt reference circuit terminal 6 and terminal 5.
    6. ⇒If greater than the specified value, test the 5-volt reference circuit for an open/high resistance.
  6. Test for less than 1 ohm between the signal circuit terminal 12 and terminal 1.
    7. ⇒If greater than the specified value, test the signal circuit for an open/high resistance.
  7. Test for less than 1 ohm between the ground circuit terminal 11 and terminal 4.
    8. ⇒If greater than the specified value, test the ground circuit for an open/high resistance.
  8. Test for infinite resistance between the 5-volt reference circuit terminal 6 and ground.
    9. ⇒If not the specified value, test the 5-volt reference circuit for a short to ground.
  9. Test for infinite resistance between the signal circuit terminal 12 and ground.
    10. ⇒If not the specified value, test the signal circuit for a short to ground.
  10. Enable the TPM learn mode. Verify all 4 sensor locations, IDs, and tire pressures match what the scan tool displays.
    11. ⇒If the scan tool data does not display, replace the tire pressure receiver module. If DTC sets again, replace the tire pressure control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Tire Pressure Indicator Sensor Replacement
    •  Tire Pressure Sensor Learn
    •  Control Module References for module replacement, setup, and programming