Circuit Description
The electronic suspension control (ESC) module performs internal checks of all internal program and data memory spaces. Additionally, various internal functions and data communications are monitored for valid operation.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0550 Electronic Control Unit (ECU) Performance
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The DTC is set when the ESC module detects an internal hardware fault. |
| • | The fault is detected during 3 consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with the scan tool. |
Action Taken When the DTC Sets
Depending upon which internal functions are affected by the fault condition, the ESC module will take one of 2 sets of actions:
| • | If the fault condition allows continued output operation, the system will enter a Speed Dependent Damping mode, in which all 4 corners of the vehicle are concurrently driven by a fixed pulse width modulation (PWM) duty cycle, which increases as a function of vehicle speed. The SERVICE SUSPENSION SYS message will be displayed. |
| • | If the fault is more severe, the control module will disable ALL dampers by commanding 0 percent PWM duty cycle, disabling the damper switched battery circuit, and sending a message to the powertrain control module (PCM) to limit vehicle speed. The VEHICLE SPEED LIMITED TO XXX MPH and SERVICE SUSPENSION SYS messages will be displayed. |
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 senses the hardware fault and the ignition is cycled OFF and ON. The DTC will clear if the fault does not return after 50 consecutive ignition cycles. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step checks to see if the fault condition is active or intermittent.
-
This step checks to see if a history DTC C0550 will return.
-
This step checks to see if the vehicle has a known intermittent condition.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Suspension Controls Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Inspect for DTC C0550. Is DTC C0550 displayed as a CURRENT fault, not a HISTORY fault? | Go to Step 5 | Go to Step 3 | |
Does the DTC reset? | Go to Step 5 | Go to Step 4 | |
Has this vehicle been serviced for DTC C0550 previously? | Go to Step 5 | Go to Step 6 | |
5 | Replace the electronic suspension control (ESC) module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the DTC reset? | Go to Step 2 | System OK |
