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 CJB. Operation of the HDC relay is controlled by the ABS module switching the coil to ground. The 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.