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.
C0577, C0579, C0582, C0584, C0587, C0589, C0592 or C0594
In order to test for the conditions that set a DTC C0577, C0579, C0582, C0584, C0587, C0589, C0592 or C0594, 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 that the voltage levels detected in both tests are lower than expected, a malfunction is present and a DTC will set.
Conditions for Running the DTC
C0577, C0579, C0582, C0584, C0587, C0589, C0592 or C0594
The following conditions must be present to run the DTC:
| • | The ignition ON. |
| • | The ESC module in command ON state. |
| • | The ESC function enabled. |
Conditions for Setting the DTC
C0577, C0582, C0587 or C0592
The ESC module detects a low voltage level, which is a short to ground on the actuator control circuit during 2 diagnostic tests performed.
C0579, C0584, C0589 or C0594
The ESC module detects a low voltage level, which is an open circuit on the actuator control circuit during 2 diagnostic tests performed.
Action Taken When the DTC Sets
C0577, C0582, C0587 or C0592
The following actions will occur when a DTC sets:
| • | Stores a DTC C0577, C0582, C0587 or C0592 in the ESC memory. |
| • | Commands 0% PWM duty cycle in order to disable all 4 actuators. |
| • | Sends a message to the IPC to display the SERVICE RIDE CONTROL and SHOCKS INOPERATIVE messages. |
| • | Sends a message to the PCM to limit the speed. The powertrain control module (PCM) then sends a message to the instrument panel cluster (IPC) to display the MAXIMUM SPEED 129 km/h (80 mph) message. |
C0579, C0584, C0589 or C0594
The following actions will occur when a DTC sets:
| • | Stores a DTC C0579, C0584, C0589 or C0594 in the ESC memory. |
| • | Commands 0% PWM duty cycle in order to disable the actuator. |
| • | Sends a message to the IPC to display the SERVICE RIDE CONTROL message. |
Conditions for Clearing the DTC
C0577, C0582, C0587 or C0592
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 a low voltage level, which is a short to ground 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. |
| • | Using a scan tool. |
C0579, C0584, C0589 or C0594
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 a low voltage level, which is an open circuit 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. |
| • | Using a scan tool. |
Diagnostic Aids
C0577, C0582, C0587 or C0592
The following condition may cause an intermittent malfunction to occur:
| • | There is an intermittent short to ground on the actuator control circuit. |
| • | There is an internal shock absorber actuator short. |
| • | If the conditions for a DTC C0577, C0582, C0587 or C0592 are current, the ESC module will disable all four actuators by commanding 0% duty cycle, and the 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 absorber 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. |
C0579, C0584, C0589 or C0594
The following conditions may cause an intermittent malfunction to occur:
| • | There is an intermittent open on the actuator control or supply circuits. |
| • | There is an internal shock absorber actuator open or high resistance value. |
| • | If the conditions for a DTC C0579, C0584, C0589 or C0594 are current, the ESC module will disable the actuator by commanding 0% duty cycle and the vehicle will experience a soft ride condition on the side of the vehicle. |
| • | 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 refer to the step numbers on the diagnostic table.
-
This step tests for short to ground and short to B+ on the control circuit.
-
This step tests for continuity from the ESC module on the control circuit and the low reference circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Suspension Controls Schematics Connector End View Reference: Suspension Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Vehicle in Vehicle System Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the resistance measure within the specified value? | 0.5-2.0 ohms | Go to Step 3 | Go to Step 7 |
Test the damper control circuit of the actuator for a short to ground and short to battery. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 4 | |
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 in Wiring Systems. Did you find and correct the condition? | -- | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
7 | Replace the applicable shock absorber. Refer to Shock Absorber Replacement in Front Suspension or Shock Absorber Replacement in Rear Suspension. Did you complete the replacement? | -- | Go to Step 9 | -- |
8 | Replace the ESC module. Refer to Electronic Suspension Control Module Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
