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Home >> GMC >> 2001 >> C3500 HD 8.1 G, Standard >> Repair and Diagnosis >> Suspension >> Electronic Suspension >> Electronic Suspension - Suspension Damping & Automatic Level Control >> Diagnostic Information and Procedures >> DTC C0655 >> Test Description

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. 2 

    Command both the ON and OFF states. Repeat the commands as necessary.

  2. 3 

    Tests the coil of the relay for continuity.

  3. 4 

    Tests for voltage at the coil side of the compressor motor relay. The IGN 3 fuse supplies power to the coil side of the compressor motor relay.

  4. 5 

    Verifies that the suspension control module is providing ground to the compressor motor relay.

  5. 6 

    Tests if ground is constantly being applied to the compressor motor relay.

  6. 7 

    Test for a short to voltage or an open in the control circuit of the compressor motor relay.

  7. 13 

    The replacement suspension control module must be calibrated.

DTC C0655

Step Action Value(s) Yes No
Schematic Reference: Suspension Controls Schematics 
1 Did you perform the RTD Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Real Time Damping 
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the compressor ON and OFF.
Does the compressor turn ON and OFF with each command?		 - Go to Diagnostic Aids Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the compressor motor relay.
  3. Measure the resistance of the relay coil, (across terminals 85 and 86).
Does the resistance measure within the specified value?		 30-90 Ω Go to Step 4  Go to Step 12 
4 
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the coil side feed circuit of the compressor motor relay with a test lamp that is connected to a good ground. Refer to Circuit Testing in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 5  Go to Step 11 
5 
  1. Connect a test lamp between the control circuit of the compressor motor relay and the coil side feed circuit of the compressor motor relay. Refer to Circuit Testing in Wiring Systems.
  2. With a scan tool, command the compressor ON and OFF .
Does the test lamp turn ON and OFF with each command?		 - Go to Step 9  Go to Step 6 
6  Does the test lamp remain illuminated with each command? - Go to Step 8  Go to Step 7 
7  Test the control circuit of the compressor motor relay for a short to voltage and an open. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 10 
8 Test the control circuit of the compressor motor relay for a short to ground. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 10 
9 Inspect for poor connections at the compressor motor relay. 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 14  Go to Step 12 
10 Inspect for poor connections at the harness connector of the suspension control module. 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 14  Go to Step 13 
11 Repair the coil side feed circuit of the compressor motor relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 14  -
12 Replace the compressor motor relay.
Did you complete the replacement?		 - Go to Step 14  -
13 
IMPORTANT:

After replacement, use the scan tool to perform the set up procedure (re-calibrate) located under Special Functions (F8: Recalibration) for the suspension control module.

Replace the suspension control module. Refer to Electronic Suspension Control Module Replacement (Suburban/Yukon XL) , Electronic Suspension Control Module Replacement (Tahoe/Yukon) .Did you complete the replacement?		 - Go to Step 14  -
14
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle (road test) within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 2  System OK
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