Test Description

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2004 Chevrolet Corvette. 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. 3:  Tests the ability of the EBCM to control the pump motor. If the test lamp illuminates, the pump motor circuit within the EBCM is good.
DTC C1218

Step Action Yes No
Schematic Reference:  ABS Schematics  
Connector End View Reference:  ABS Connector End Views  
1 Did you perform the ABS Diagnostic System Check? 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?
Go to Step 3  Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
  1. Turn OFF the ignition.
  2. Disconnect the pump motor harness pigtail connector of the BPMV.
  3. Connect a test lamp between the pump motor circuits at the pump motor connector of the EBCM using the J 35616  connector test adapter kit.
  4. Use the scan tool in order to clear the DTCs.
  5. With the scan tool, perform the Pump Motor Test.
Does the test lamp illuminate?
Go to Step 5  Go to Step 4 
4
  1. Turn OFF the ignition.
  2. Disconnect the EBCM harness connector.
  3. Connect the J 39700 universal pinout box using the J 39700-300  cable adapter to the EBCM harness connector only. See Special Tools and Equipment .
  4. Test both ground circuits of the EBCM including the EBCM ground for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 9  Go to Step 6 
5 Inspect for poor connections at the pump motor harness pigtail connector of the BPMV. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 9  Go to Step 7 
6 Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 9  Go to Step 8 
7 Replace the BPMV. Refer to Brake Pressure Modulator Valve (BPMV) Replacement .
Did you complete the repair?
Go to Step 9  -
8 Replace the EBCM. Refer to Electronic Brake Control Module Replacement .
Did you complete the repair?
Go to Step 9  -
9
  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
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.