Illuminated red warning indicator which mounts horizontally on the far left of the dashboard. This switch operated by measuring the hydraulic pressure differences between the front and rear – if the pressure difference becomes too great (aka you have a leak), a piston on the brake line connector will move and complete the circuit, causing the lamp to illuminate.

Note: You can test the list to see if it is working by pressing on the end of the switch face plate away from the red lens – it should illuminate when this is done.

Note 2: 68-69 had a black bezel with 3 terminals on the back which is no longer available. This is the available replacement.