C0665

DTC C0665





Circuit Description
The ESC module receives a chassis pitch angle information from the PCM on the chassis pitch angle signal circuit. Under normal conditions, this signal is 5 volt (+/- 0.5 volt) ref. The PCM then grounds the chassis pitch signal circuit when the vehicle is accelerating rapidly or braking hard. When the PCM grounds the chassis pitch angle signal circuit, the circuit goes low to about 0 volts, the ESC module commands all four shock absorber solenoids to a firm position. The PCM calculates the chassis pitch information based on the engine torque and the vehicle braking force. The ESC module also performs a test on the chassis pitch angle circuit when the ignition switch is turned to RUN. The ESC module sends a chassis pitch request to the PCM on the serial data line. The PCM then grounds the chassis pitch input circuit, pulling the circuit low for 5 seconds and returns to normal operation.

Conditions for Running the DTC
^ The ignition ON.
^ The RTD function enabled.

Conditions for Setting the DTC
^ After the ignition is turned to RUN, the ESC module does not detect a low to high transition on the chassis pitch angle signal circuit from the PCM.
^ The ESC module will continue to send a request every 4 minutes to the PCM in order to retest for a chassis pitch circuit malfunction.
^ The condition must be detected within 31 seconds.

Action Taken When the DTC Sets
^ Stores a DTC C0665 in the ESC memory.
^ Ignores the chassis pitch angle.
^ Sends a message to the IPC to display the SERVICE RIDE CONTROL message.

Conditions for Clearing the DTC
^ After the ignition is cycled, or after 4 minutes, the ESC module detects a low to high transition on the chassis pitch angle signal circuit from the PCM within 31 seconds.
^ 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
^ The following conditions may cause an intermittent malfunction to occur:
- An intermittent open or short on the chassis pitch angle signal circuit.
- An intermittent open or short to ground on the serial data line.
^ An intermittent short to ground or open on the chassis pitch angle signal circuit may cause a random firm/soft ride condition.
^ If the DTC is a history DTC, the problem may be intermittent. Using a scan tool, monitor the Chassis Pitch Angle while moving the wiring and the connectors. This can often cause the malfunction to appear.
^ The scan tool can command the PCM to ground the chassis pitch input circuit. This can be used for diagnostic purposes.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Tests the normal state of the chassis pitch angle using a scan tool. The scan tool will display normal state as Inactive, and Active with chassis pitch angle detected.
3. Tests if the PCM is supplying a constant ground on the chassis pitch angle signal circuit.
4. Tests if the ESC module is able to detect a change in chassis pitch angle. With the chassis pitch angle signal circuit jumpered to ground, the scan tool will display Chassis Pitch Angle status as Active.