A retainer apparatus including a first retainer portion, a second retainer portion, a wireless transceiver, and a sensor contained within at least one of the first retainer portion and the second retainer portion. The retainer apparatus includes the first retainer portion configured to be slidably attached to a first harness strap and a second retainer portion configured to be slidably attached to a second harness strap. The first retainer portion is removably attached to the second retainer portion. The sensor is configured to detect the first retainer portion being disconnected from the second retainer portion and generate a warning signal. The wireless transceiver is configured to wirelessly transmit the warning signal to a controller in a vehicle to activate an audible warning alert to warn a user in the vehicle of the first retainer portion being disconnected from the second retainer portion.