Circuit Description
The strut actuator is controlled by the electronic suspension control (ESC) module with a pulse-width modulation (PWM) signal. Switching the voltage ON and OFF at a high frequency (2.0 kHz), or pulse width modulating, controls the amount of current delivered to the actuator. By controlling the amount of current to the actuator the ESC module controls the damping force in the strut. A higher level of damping force is achieved by providing correspondingly higher current levels, relating to higher percentages of PWM duty cycle. The default damper state (no battery voltage) is one that provides a minimum damping force.
The ESC module periodically commands each strut actuator to a preset PWM duty cycle in order to override the normal PWM command. During this preset PWM duty cycle, the ESC module is able to perform a diagnostic test on each strut actuator to determine if a malfunction is present. The preset PWM command can be either an OFF or ON state duty cycle.
DTC C0577, C0582, C0587, or C0592
In order to test for the conditions that set DTC C0577, C0582, C0587, or C0592, the ESC module must first command the strut actuator OFF. If the voltage detected in the damper control circuit during the OFF state is less than a preset value, the test is repeated. If the ESC module again detects voltage less than the preset value, a DTC will be set.
DTC C0578, C0583, C0588, or C0593
In order to test for the conditions that set DTC C0578, C0583, C0588, or C0593, the ESC module must first command the strut actuator ON. If the voltage detected in the damper control circuit during the ON state is greater than a preset value, the test is repeated. If the ESC module again detects voltage greater than the preset value, a DTC will be set.
DTC C0579, C0584, C0589, or C0594
In order to test for the conditions that set DTC C0579, C0584, C0589, or C0594, the ESC module must first command the solenoid OFF. If the voltage detected in the damper control circuit during the OFF state is between two preset values, the test is repeated. If the ESC module again detects voltage between two preset values, a DTC will be set.
Conditions for Running the DTC
DTC C0577, C0579, C0582, C0584, C0587, C0589, C0592, or C0594
The following conditions must be present to run the DTC:
| • | The ignition is ON. |
| • | The ESC module is in command OFF state. |
DTC C0578, C0583, C0588, or C0593
The following conditions must be present to run the DTC:
| • | The Ignition is ON. |
| • | The ESC module is in command ON state. |
Conditions for Setting the DTC
DTC C0577, C0582, C0587, or C0592
The following conditions must be present to set the DTC:
| • | The ESC module detects voltage less than a preset value during 2 consecutive OFF state tests. |
| • | The fault is detected during 3 consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool. |
DTC C0578, C0583, C0588, or C0593
The following conditions must be present to set the DTC:
| • | The ESC module detects voltage greater than a preset value during 2 consecutive ON state tests. |
| • | The fault is detected during 3 consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool. |
DTC C0579, C0584, C0589, or C0594
The following conditions must be present to set the DTC:
| • | The ESC module detects voltage between 2 preset values during two consecutive OFF state tests. |
| • | The fault is detected during 3 consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool. |
Action Taken When the DTC Sets
DTC C0578, C0579, C0583, C0584, C0588, C0589, C0593, or C0594
The following actions will occur when a DTC is set:
| • | The SERVICE SUSPENSION SYS message will be displayed. |
| • | The affected strut actuator will be disabled by commanding 0 percent PWM duty cycle. |
DTC C0577, C0582, C0587, or C0592
The following actions will occur when a DTC is set:
| • | The SERVICE SUSPENSION SYS and SPEED LIMITED TO XXX messages will be displayed. |
| • | ALL the strut actuators will be disabled by commanding 0 percent PWM duty cycle. |
| • | The damper relay control switch will be opened and the damper relay de-energized. |
| • | The vehicle speed will be limited. |
| • | The vehicle ride will be soft. |
Conditions for Clearing the MIL/DTC
| • | The scan tool can be used to clear the DTC. |
| • | The DTC is saved as history when the ESC module no longer detects the fault during 2 consecutive diagnostic tests. The DTC will clear if the fault does not return after 50 consecutive ignition cycles. |
Diagnostic Aids
| • | If multiple strut actuator circuit DTCs are stored along with DTC C0690, diagnose DTC C0690 first. |
| • | If the DTC is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Tests for a short or an open in the strut actuator coil.
-
Tests for voltage at the coil side of the strut actuator.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Suspension Controls Schematics | ||||
1 | Did you perform the Electronic Suspension Control Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Electronic Suspension Control |
Does the resistance measure within the specified value? | 9.5-15.5 ohms | Go to Step 3 | Go to Step 8 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 5 | |
4 | Test the strut motor decrease damping circuit of the strut actuator for a short to ground, a short to voltage, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 |
5 | Test the strut motor increase damping circuit of the strut actuator for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 10 | Go to Step 7 |
6 | Inspect for poor connections at the harness connector of the strut actuator. 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 10 | Go to Step 7 |
7 | Inspect for poor connections at the harness connector of the Electronic Suspension Control (ESC) 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 10 | Go to Step 9 |
8 | Replace the strut/shock absorber. Refer to Strut Assembly Replacement in Front Suspension or Shock Absorber Replacement in Rear Suspension. Did you complete the replacement? | -- | Go to Step 10 | -- |
9 |
Important: Perform the set up procedure for the ESC module. Replace the ESC module. Refer to Electronic Suspension Control Module Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
