GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 DTC 🢒 DTC C0657 or C0658

Circuit Description

The Automatic Level Control compressor is switched ON and OFF using an Electronic Level Control (ELC) compressor relay which is controlled by the Continuously Variable Road Sensing Suspension (CVRSS) module. The CVRSS module circuitry provides a switched path to ground (low-side drive) whenever compressor activity is required. This drive circuit is also continually monitored to determine if the voltage level agrees with the commanded state.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

DTC C0657

The following conditions must be present to set the DTC:

    • The CVRSS module detects voltage less than a preset value in the compressor motor control circuit during a compressor OFF state test.
    • The fault is detected during three consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool.

DTC C0658

The following conditions must be present to set the DTC:

    • The CVRSS module detects voltage greater than a preset value in the compressor motor control circuit during a compressor ON state test.
    • The fault is detected during three consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool.

Action Taken When the DTC Sets

The ELC compressor relay output drive is disabled for the remainder of the ignition cycle.

Conditions for Clearing the MIL/DTC
    • The scan tool can be used to clear the DTC.
    • The DTC is saved as history when the CVRSS module no longer sees an out of range voltage condition in the compressor motor control circuit. The DTC will clear if the fault does not return after 50 consecutive ignition cycles.

Diagnostic Aids

These DTCs are set only by electrical problems with the ELC compressor relay coil circuit. Compressor motor problems and pneumatic leakage problems do not set these DTCs.

Test Description

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

  1. Listen for an audible click when the ELC Relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

  2. Tests for voltage at the coil side of the ELC Relay . The ELC Fuse supplies power to the coil side of the ELC Relay.

    3.

  3. Verifies that the CVRSS module is providing ground to the ELC Relay.

    4.

  4. Tests if ground is constantly being applied to the ELC Relay.

Step

Action

Yes

No

Schematic Reference: Automatic Level Control Schematics

1

Did you perform the Road Sensing Suspension Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Road Sensing Suspension

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the ELC Relay ON and OFF.

Does the ELC Relay turn ON and OFF with each command?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the ELC Relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side feed circuit of the ELC Relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

  1. Connect a test lamp between the coil side feed circuit of the ELC Relay and the compressor control circuit of the ELC Relay.
  2. With a scan tool, command the ELC Relay ON and OFF .

Does the test lamp turn ON and OFF with each command?

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each command?

Go to Step 7

Go to Step 6

6

Test the compressor control circuit of the ELC Relay for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the compressor control circuit of the ELC 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 13

Go to Step 9

8

Inspect for poor connections at the ELC 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 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the CVRSS 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 13

Go to Step 12

10

Repair the coil side feed circuit of the ELC Relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the ELC Relay.

Did you complete the replacement?

Go to Step 13

--

12

Important: Perform the set up procedure for the CVRSS module.

Replace the CVRSS module. Refer to Electronic Suspension Control Module Replacement .

Did you complete the replacement?

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK