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Home >> Cadillac >> 2003 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 633 (Antilock Brake System, Traction Control System & Stability Control System) >> Diagnostic Information and Procedures >> DTC C0121: Valve Relay Circuit >> Test Description
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Test Description

WARNING: This page is about a different car, the 2004 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 2:  Determines whether the DTC is current.
DTC C0121

Step Action Values Yes No
Schematic Reference: ABS Schematics 
Connector End View Reference: ABS Connector End Views 
1 Did you perform the Diagnostic System Check - ABS? - Go to Step 2  Go to Diagnostic System Check - ABS 
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to clear the DTCs.
  4. With the scan tool, perform the Automated Test.
Does the DTC reset as a current DTC?		 - Go to Step 3  Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
3
  1. Disconnect the pump motor harness pigtail connector of the BPMV.
  2. Measure the resistance between each pump motor control circuit and the housing of the BPMV at the pump motor harness pigtail connector of the BPMV.
Does the DMM display the specified value?		 OL Go to Step 5  Go to Step 4 
4 Replace the EBCM and the BPMV. Refer to Electronic Brake Control Module Replacement (CTS)  or Electronic Brake Control Module Replacement (CTS-V)  and Brake Pressure Modulator Valve (BPMV) Replacement (CTS)  or Brake Pressure Modulator Valve (BPMV) Replacement (CTS-V) .
Did you complete the repair?		 - Go to Step 6  -
5 Replace the EBCM. Refer to Electronic Brake Control Module Replacement (CTS)  or Electronic Brake Control Module Replacement (CTS-V) .
Did you complete the repair?		 - Go to Step 6  -
6
  1. Use the scan tool in order to clear the DTCs.
  2. With the scan tool, perform the Automated Test.
Does the DTC reset?		 - Go to Step 2  System OK
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