I don't know if mine does it without the parking brake set. When I stop my truck, I always step on the park brake and then shift to park. I broke a park pin one time in an older truck and it rolled into my dad's big truck, let's just say I learned that lesson well as a teenager. Anyhow, I know it's supposed to be a requirement, but every truck is different and I see that you have found the wires to the park brake switch. I don't know if it closes a ground signal or is 12 volts hot, but if it's ground you could use the switch for the power and signal power to a relay and the ground from the park brake switch to close the relay and provide the 12V+ to the blue w/ yellow stripe wire.....If your truck is idling up, you have the right wires, any other wires will not work and any 12V+ signal to the blue w/ yellow stripe wire will provide the same effect, the only reason we use the blue w/ white stripe wire is that it is a body builder supplied wire for installing PTO's etc. and it works on ignition power and was in the PTO installation instructions, which made it easy and the location is easy to access and it's an "empty" wire end. There are other options if the park brake switch is 12V+ in and out when closed. I can help you if you let me know what you find in detail. Good luck zoom..... Mat