C1780

Circuit Description
The ESC module receives a PWM steering position signal from the EBTCM on CKT 914. The ESC module uses this signal in order to determine the shock absorber control levels and will command a more firm setting if the vehicle is in a turn. The ESC module monitors the steering position circuit and can determine if a valid signal is sent from the EBTCM.

Conditions for Setting the DTC
- The ESC module does not detect a valid steering position signal from the EBTCM.
- The condition must be detected for 5 seconds.

Action Taken When the DTC Sets
- Stores a DTC C1780 in the ESC memory.
- Ignores the steering position signal input.
- Will continue to control the shock absorbers using the lateral acceleration data sent from the EBTCM on the serial data line.
- Sends a message to the IPC to display the SERVICE RIDE CONTROL message.

Conditions for Clearing the DTC
- The ESC module detects a valid steering position signal from the EBTCM.
- A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
- The IPC clearing DTCs feature.
- Using a scan tool.

Diagnostic Aids
The following conditions may cause an intermittent malfunction:
- An intermittent open or short (to ground or to voltage) on the steering position sensor CKT 914.
- Intermittent operation of the EBTCM. Refer to ABS Diagnostic System Check Diagnostic System Check in AIR BAGS AND SEAT BELTS.
- If the ESC module does not receive a valid steering position signal from the EBTCM, the Real Time Dampening (RTD) system will still function, but will ignore the steering position signal. The RTD system uses lateral acceleration data sent from the EBTCM on the serial data line in order to substitute for a loss of the steering position signal.
- An intermittent open or short (to ground or to voltage) on the steering position sensor 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 steering position sensor circuit while moving the related wiring and connectors. This can often cause the malfunction to appear.


Test Description
The numbers below refer to the step numbers on the diagnostic table:
2. This step checks if any ABS/TCS DTCs are present. The EBTCM provides the ESC module with steering position data, therefore all ABS/TCS DTCs that are associated with the steering position sensor must be diagnosed and corrected before attempting to diagnose a DTC C1780.
3. This step checks if the ESC module is able to receive steering position data from the EBTCM.
4. This step checks for opens or shorts (to ground or to voltage) on the steering position signal CKT 914.
5. This step checks for an intermittent malfunction and requests a thorough inspection of the related steering position sensor circuit wiring and connectors.