Very first test is to have someone behind the coach and verify exactly when your brake lights come on as you slowly apply the service brakes. Same for retarder. The other option is to do it at night with the rear view camera alerting you as to when the brake lights come on.
Brett
Elliott, I would guess that you have one or possibly two problems:
The King Control/Cruise Control (KC/CC) will interrupt CC when it senses 12Vdc in your Brake light circuit (and Steve has verified, with his black box, that that is working).
The 12Vdc is/should be sensed downstream of the two pressure switches mounted up high on your street-side, forward-most compartment, front panel.
Those pressure switches monitor your front and rear air brake system pressures. As your brake treadle is depressed, these switches actuate, at their set points, allowing 12Vdc to pass to the brake light filament wires. The KC/CC also has a sensing wire that lands on one or both of these switches, that provides the ground path through the brake light filaments, that the KC/CC must have in order to allow throttle responses > 1500RPM.
These sealed pressure switches are pretty reliable, but it is possible that one or both have shifted in setpoint or may be otherwise unreliable (contacts may be arced and unreliable). The switches are not adjustable and can't be disassembled.
Because these switches are located in an open, "wet" compartment, the more likely scenario is that the switch
terminals have corroded or become loose and you have one or more unreliable circuits for the KC/CC (FT also common-ed up several sets of wires on some of these terminals, which leads to reliability issues in unprotected environments).
At any rate, I would try to make the problem repeatable. Then I would take the wires off, one terminal at a time, clean, lube and re-land them and see if/where it makes your problem go away. Then you may have found it. Soldering any common wire sets together, for each terminal, is one way to reduce future aggravations.
If that doesn't do it, but you can see with a voltmeter that it takes too much treadle pressure to actuate one or both of the two pressure switches, then you have pressure switches to replace.
For your reading pleasure, you may want to read through the following thread on this forum:
Allison AW or King Throttle Control (or other) problem (http://www.foreforums.com/index.php?topic=8088.msg35438#msg35438)
Hope this helps:
Neal