For 1990-2009 cars

### Circuit Description

The electronic suspension control (ESC) module uses the pulse-width modulation (PWM) method in order to control each shock absorber actuator. Switching the voltage ON and OFF at each shock absorber actuator, or pulse width modulating, limits the amount of current supplied to that particular actuator. The ESC module periodically commands each shock absorber to a set PWM duty cycle in order to override the normal PWM command. During this set PWM duty cycle, the ESC module is able to perform a diagnostic test on each shock absorber actuator, and can determine if a malfunction is present. The ESC module is only able to detect certain malfunctions during a given state, which are ON or OFF.

In order to test for the conditions that set a DTC C0575, C0580, C0585, or C0590, the ESC module must first command the actuator ON. The ESC module must be in a command ON state. If a low voltage level is detected in the actuator control circuit during the ON state, the test is again repeated. If the ESC module determines the voltage levels detected in both tests are lower than expected, a malfunction is present and a DTC will set.

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC C0575 Left Front Solenoid/Motor/Actuator Circuit

• | DTC C0580 Right Front Solenoid/Motor/Actuator Circuit

• | DTC C0585 Left Rear Solenoid/Motor/Actuator Circuit

• | DTC C0590 Right Rear Solenoid/Motor/Actuator Circuit

This vehicle has DTCs which include DTC symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description.

DTC Symptom | DTC Symptom Descriptor
--- | ---
01 | Short to Battery
02 | Short to Ground
04 | Open Circuit

### Conditions for Running the DTC

The following conditions must be present to run the DTC:

• | Turn the ignition ON.

• | The ESC module must be in a command ON State.

• | The ESC function is enabled.

### Conditions for Setting the DTC

The ESC module detects an abnormal voltage level, which is a short to ground, open circuit or short to battery on the actuator control circuit during 2 diagnostic tests performed.

### Action Taken When the DTC Sets

• | Stores a DTC C0575, C0580, C0585, or C0590 in the ESC memory.

• | Commands 0 percent PWM duty cycle in order to disable all 4 actuators.

• | Sends a message to the instrument panel cluster (IPC) to display the SERVICE RIDE CONTROL message.

• | Sends a message to the powertrain control module (PMC) to limit the speed. The PCM then sends a message to the IPC to display the MAXIMUM SPEED 129 km/h (80 mph) message.

### Conditions for Clearing the DTC

the following conditions must exist to clear the DTC:

• | The ignition must be cycled before this DTC can change from current to history even if the malfunction is no longer present.

• | The ESC module no longer detects an abnormal voltage level, which is a short to ground, open circuit or short to battery on the actuator control circuit during two diagnostic tests.

• | A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

• | Use the IPC clearing DTC feature.

• | Use a scan tool.

### Diagnostic Aids

The following conditions may cause an intermittent malfunction to occur:

• | There is an intermittent short to ground, open circuit or short to battery on the actuator control circuit.

• | There is an internal shock absorber actuator short.

• | If the conditions for a DTC C0575, C0580, C0585, or C0590 are current, the ESC module will disable all four actuators by commanding 0 percent duty cycle, and the real-time damping (RTD) relay. The vehicle will experience a soft ride condition on the side of the vehicle.

• | The RTD relay provides supply voltage to all four shock absorbers actuators; therefore, multiple shock absorber actuator DTCs which are open or short to ground may also be stored along with a DTC C0550. Always diagnose a DTC C0550 first before attempting to diagnose multiple shock absorber actuator DTCs.

• | If a short to ground is present on the actuator supply circuit, the RTD fuse will open and DTC C0550 may set.

• | If the DTC is a history DTC, the problem may be intermittent. Using a scan tool, cycle the shock absorber actuator while moving the wiring and the connectors. This can often cause the malfunction to occur.

### Test Description

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

1. This step tests for short to ground and short to B+ on the control circuit.

2. This step tests for continuity from the ESC module on the control circuit and the low reference circuit.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Electronic Suspension Control Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Disconnect the shock absorber connector.
2. Measure the resistance of the shock absorber actuator.

Does the resistance measure within the specific range?

0.5-2.0

Go to Step 3

Go to Step 7

3 | Test the damper control circuit of the actuator for a short to ground and short to battery. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 4
4 |

1. Disconnect the electronic suspension control (ESC) module.
2. Check continuity from the ESC module to the damper actuator connector on both the control circuit and the reference low circuit. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 5

5 | Inspect for poor connections at the actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | 5 V | Go to Step 9 | Go to Step 6
6 | Inspect for poor connections at the harness connector to the ESC module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | 5 Ω | Go to Step 9 | Go to Step 8
7 | Replace the applicable shock absorber. Refer to Shock, Shock Component, and/or Spring Replacement and Shock Absorber Replacement. Did you complete the replacement? | -- | Go to Step 9 | --
8 | Replace the ESC module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | --
9 |

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