C1743: OBD-II code C1743 flags a fault in the vehicle speed signal reaching the suspension control module — damping and levelling algorithms lose their speed input.

Symptoms

• The 'Service Ride Control' warning is displayed and adaptive damping cannot adjust to vehicle speed.
• The suspension may feel over- or under-damped because the module cannot switch between speed-dependent modes.
• Load-levelling may also be inhibited above certain thresholds because the module cannot verify motion.

Common causes

• A serial data bus fault preventing wheel-speed or vehicle-speed messages from reaching the suspension control module.
• A failed vehicle speed sensor (on older discrete-wire vehicles) with an open or intermittent signal.
• Damaged wiring or a bad splice on the discrete speed signal line between the source module and the suspension controller.

What to do?

Scan every module for related U-codes and wheel-speed sensor codes — fix those first. Verify the suspension control module receives valid speed data with a scan tool. Repair bus wiring or replace a failed vehicle speed sensor as needed.