Line Lock Light

The only way you could do that is to wire the linelock so that the switch is in the ground leg, because that is how the brake warning lamp is wired

Then you would need at least one isolation diode to prevent interaction between the two circuits

I'm sitting here with a lap full of breakfast LOL. If I can I'll draw up a diagram and post it

So I would make
one (fused) leg into the valve hot,
diode on the 'out' leg of the valve,
into the switch? or then into the brake indicator circuit?
If i went into the switch and then out to the indicator/proportioning valve wire that would act as my ground, no? Thanks Del, as you may have gathered, I am not quite at 100 level classes on the whole wiring situation.