C1720: OBD-II code C1720 flags the left rear damper actuator circuit shorted to battery voltage — the RSS module cannot control damping at that corner.

Symptoms

• The 'Service Ride Control' warning is displayed and left rear damping reverts to a default fixed level.
• The left rear corner may feel harsher or softer than the other three because adaptive damping is inactive.
• On some vehicles the RSS module may disable adaptive control on all four corners as a safety fallback.

Common causes

• A chafed left rear damper actuator wire touching a battery-voltage source, often against a suspension bolt or bracket.
• An internally shorted damper actuator solenoid coil pulling the drive circuit to battery voltage.
• Water intrusion into the left rear damper connector causing a short between the drive wire and B+.

What to do?

Disconnect the left rear damper actuator and inspect the harness for chafing along the trailing arm. With the connector unplugged, verify no B+ voltage on the drive wire at the actuator side. Measure actuator resistance — most read 4-10 Ω when good. Replace the actuator or repair the harness.