I am thinking you are meaning to say a battery, two wires and a lightbulb. Two wires from a battery will just short out if you make the switch engage, likely burning out the switch.
If you have an air regulator with gauge, you can set it up onto the switch, and start increasing the air pressure until the light comes on. Removing the pressure should have the switch come off immediately. If it does, then your problem is the hydraulic system. Perhaps the residual pressure in the master is enough to engage the switch, or borderline to release the switch. There are identical switches that take higher pressure to engage. I had a quick look on NAPA which shows 4 similar switches for the Jeep. Two of them are listed as being for 60 to 120 pressure to close the contacts. I have seen other switches with much lower pressures listed but I'll have to check some of the NSN's at work tomorrow to confirm. If the residual pressure in your system was actually at 60 psi, I think that would have the brakes dragging.
You could also put a gauge onto the brake switch port and see what the pressure actually is after brake application, and how fast it returns to minimum. Any chance of a piece of something blocking the return port in the master cylinder? Luckily, if the switches prove to be OK, master cylinders are quite cheap in the US, usually around $40.
Last edited by rob love; 09-03-21 at 06:27.
|