PBR Air–Over–Hydraulic Brake System model CA300 help please

Hi needing some help please with CA300 brake system. Trying to workout why the low air pressure light wont go off unless you pull the park brake lever down. Have put new sensor in and still doing the samething. It is hooked up to the trailer brakes for some reason and not sure if this correct or not ? any help would be great thanks

P.S its on an International D1950

I'm wondering if it has had a low air warning switch fitted in place of the stop light switch? If so, the light will be on until the hand controlled is pulled down.

The low air switch should be at, or in the feed line from the air reservoir. There should be a brake light (brakes on) switch in the control line to the trailer.

Maybe just make sure/test that the right type of switch is fitted, i think the low air switch would be a normally closed switch, and the brake light switch would be a normally open switch.

Dolphin, Do a search on here for CA300 there is several threads about them..