[Shane]

I'm guessing that the 8.6V is voltage that is back-feeding thru the tail light? The easy way to check this is if you have access to the relay, unplug the wire that has the 8.6V on it and see if the 8.6V at the tail light is still there or goes away. If it's still there, then the voltage is coming thru the tail light onto that wire from the park light circuit. I'm a bit confused about what the relay does that you're talking about or how it's wired or what it's wired to control.....but I'm wondering if the 8.6V is just voltage that's backfeeding thru the LED's in the tail light, your solution might be to get a resistor (maybe 100 ohm or so?) and connect that from the wire that has the 8.6V on it and run the other end of the resistor to ground?

 

[Shane]

"I have disconnected every wire at the light end and only connected the brake wire and the common ground. I get 8.6V on the brake circuit even with no load on the parking light circuit."

It sounds to me like you are feeding power thru the relay coil to the brake lights? Maybe I'm not reading something right....but if you have all of the wires disconnected from the lights except for the brake circuit....and you are getting 8.6V at the lights.....it sounds to me like you are feeding power to the brake lights thru the relay COIL and not the relay CONTACTS?

"I should have power on my brake lights at all times, waiting for a trigger from the brake switch. When I turn the stalk a nominal voltage is supplied to the brake circuit."

No....you should not have power on the brake lights at all times. The only time you should have power to the brake lights is when you step on the brakes and the brake switch closes and supplies power to the brake lights....thru the brake switch.....no relay required. The brake lights should not be connected to the stalk in any way at all.....brake light wire comes from the fuse block, to the brake switch and then thru the brake switch directly to the brake lights.