C1786: OBD-II code C1786 flags a fault in the damper control relay — the relay that supplies power to the ICCS2/RSS damper outputs is not operating correctly.

Symptoms

• The 'Service Ride Control' warning is displayed and adaptive damping is completely disabled across all four corners.
• None of the four damper actuators respond to commands because the shared power feed relay isn't energising.
• The ride feels like a passive suspension because no dampers can be driven by the ICCS2 module.

Common causes

• A failed damper control relay with worn contacts or an open coil, unable to energise reliably.
• A blown fuse in the relay's supply circuit, or corroded pins in the relay socket, preventing normal operation.
• A failed ICCS2/RSS module driver that no longer commands the relay properly.

What to do?

Locate the damper control relay per the service manual and swap in a known-good relay to test. Verify the relay fuse is intact and the socket pins are clean. Check that the ICCS2/RSS module is commanding the relay coil with a scan tool. Replace the relay or module driver as needed.