GM Service Manual Online
For 1990-2009 cars only

Object Number: 541208  Size: LF
Data Link Connector Schematics
Data Link Connector Schematics
Ground Distribution Schematics
Power Distribution Schematics
Power and Grounding Components
Tire Pressure Monitoring System Schematics
HVAC Blower Control Schematics

Circuit Description

When the diagnostic procedures indicate that receiver replacement is necessary, program the service replacement receiver to the vehicle's TPM sensors. Each sensor's unique identification code can be programmed into the receiver's memory. After the program mode is entered, each sensor must transmit its identification code in sequence. DTC C2121 is set at the time of manufacture and will automatically be cleared when the programming procedure is properly completed. This DTC can only be set once during the life of the receiver.

Conditions for Setting the DTC

This DTC is automatically set at the time of manufacture. No TPM sensors are programmed in the receiver's memory.

Action Taken When the DTC Sets

    • Stores a DTC C2121 in the receiver's memory
    • No driver warning message will be display for this DTC.
    • The IPC will not display tire pressure data.

Conditions for Clearing the DTC

The receiver clears this DTC automatically when TPM sensor programming is complete.

Diagnostic Aids

    • The service replacement receivers will have DTC B2805 and DTC C2121 stored in the receiver's memory and will not clear until the receiver is properly programmed. When diagnostic procedures indicate that receiver replacement is necessary, program all TPM sensors and RFA transmitters to the replacement receiver.
    • Check that a service replacement receiver was not installed without programming the TPM sensors to that receiver.
    • Clear the receiver's diagnostic memory before road testing the vehicle whenever a TPM sensor is replaced in order to avoid reading the original DTC stored in the memory.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. This test checks if the IPC can enter the TIRE TRAINING mode. If the display is blank, or if the DIC buttons do not respond when pressed, refer to IPC Diagnostic System Check.

  2. This test determines if the TPM sensors can properly transmit their identification codes. (If the horn did not sound during the test, the receiver was unable to receive a TPM sensor identification code.)

  3. This test determines if all of the TPM sensors are on the vehicle and undamaged.

  4. This test checks if the TPM sensors corrected the malfunction.

  5. This test will determine if the RFA transmitters are currently programmed. If the RFA transmitters are not programmed, the receiver will have a DTC B2805 stored in the memory.

DTC C2121 -- TPM System Programming Malfunction (No Sensors Programmed)

Step

Action

Value(s)

Yes

No

1

Were you sent here from the TPM Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Tire Pressure Monitoring

2

Using the buttons on the DIC, enter the TIRE TRAINING mode. Refer to Tire Pressure Monitoring Sensor Programming .

Can the programming be successfully accessed through the IPC?

--

Go to Step 3

Go to Diagnostic System Check - Instrument Cluster

3

Program all TPM sensors. Refer to Tire Pressure Monitoring Sensor Programming .

Was the programming successful?

--

Go to Step 5

Go to Step 4

4

Inspect all wheels for missing or damaged TPM sensors.

Are all sensors on the vehicle and undamaged?

--

Go to Step 9

Go to Step 7

5

  1. Clear all DTCs.
  2. Road test the vehicle above 24 km/h (15 mph) for 20 minutes.

Does DTC C2121 reset?

--

Go to Step 9

Go to Step 6

6

  1. Select the display RFA DTC function with the scan tool.
  2. Check for RFA DTC B2805.

Is DTC B2805 stored?

--

Go to Step 8

System OK

7

  1. Replace the damaged or missing TPM sensor(s). Refer to Low Tire Pressure Indicator Sensor Replacement .
  2. Program all TPM sensors. Refer to Tire Pressure Monitoring Sensor Programming .

Is the replacement complete?

--

Go to Step 10

--

8

Program the RFA transmitters. Refer to Transmitter Programming/Synchronization in Keyless Entry.

Was the programming successful?

--

Go to Step 10

Go to Diagnostic System Check - Remote Keyless Entry

9

  1. Replace the remote control door lock receiver. Refer to Tire Pressure Indicator Receiver Replacement .
  2. Program all TPM sensors. Refer to Tire Pressure Monitoring Sensor Programming .
  3. Program the RFA transmitters. Refer to Transmitter Programming/Synchronization in Keyless Entry.

Is the replacement complete?

--

Go to Step 10

--

10

  1. Turn the ignition to OFF.
  2. Install any components or connectors that were removed.
  3. Clear all DTCs.

Are the repairs complete?

--

Go to Diagnostic System Check - Tire Pressure Monitoring

--