The connection to the anti-lock sensor corroded away and it looks like I'd have to replace both the sensor and the cable to reconnect it. Since the the anti-lock brakes weren't very useful, I don't think I'll bother.
This means the brake warning lights are permanently on. Of course, I could just take the bulbs out, but the other functions of the warning light (parking brake on, low fluid, failure of one circuit) are probably worth keeping.
So, my question is: does anybody know what wires to cut or splice to disconnect the light from the anti-lock sensor, but allow the other functions to work?

 

Find out what the resistance is of the sensor , solder in a resistor that matches that value , the system will then work as if the problem is gone / everything normal .
Tie down this mod & coat with silicone to keep elements from affecting .

 

Something you should consider before doing that..
By by-passing a designed "safety feature" of the truck such as the ABS, you are risking having your insurance company legally be able to refuse to pay for any damages/liability you incur due to an accident.

This can also be used as the basis for a liability/negligence claim against you should it become known to the other party in an accident claim.
When you by-pass or modify something like the ABS, you are running a pretty big risk!
Its probably not worth doing...

 

You can unplug the RWAL box, that will turn off the lights but keep the foundation brake warning functions.

But what Chrisreyn said. I would fix it right if it was my truck.