HDC Relay

The HDC relay is used to illuminate the stoplamps when the brakes are activated during HDC operation and during dynamic application of the parking brake.

The HDC relay is a non-serviceable, solid state relay on the circuit board of the central junction box (CJB). Operation of the HDC relay is controlled by the anti-lock brake system (ABS) module switching the coil to ground. The anti-lock brake system (ABS) module monitors brake system hydraulic pressure and energizes the HDC relay during active braking. A pressure threshold and time filter prevent the stoplamps from flickering when HDC is braking.