C2121
DTC C2121-C2124
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this 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 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 (Description and Operation)
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
Control Module References (Programming and Relearning)for Scan Tool Information
Circuit/System Testing
1. With the scan tool, verify that DTC C2173 is not set.
• If DTC C2173 is set, refer to DTC C2173 (C2173).
2. With the scan tool, locate and record tire pressure sensors ID and locations.
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. 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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 (Verification Tests) after completing the diagnostic procedure.
* Tire Pressure Indicator Sensor Replacement (Service and Repair)
* Tire Pressure Indicator Sensor Learn (Testing and Inspection)
* Control Module References (Programming and Relearning)for module replacement, setup, and programming