A speed sensor for a wheel end that has an interior that is substantially isolated from an atmosphere around the wheel end. The speed sensor is carried by a housing of the wheel end for monitoring the rotation of the wheel end and indicating the angular velocity of the wheel end. The speed sensor includes a cable leading from the sensor to a location remote from the wheel end and further includes leads that transmit a signal and a sheath that encloses the leads. The sheath is open enough to allow a fluid to flow through its interior. A vent channel provides communication between the interior of the wheel end and the interior of the sheath on the cable.