Hello Peter,
Here is some instructions that I saved from "graphic 66". Hope it helps! Note: throttle switch=idle switch
"Check fuse #3 - this power goes to the double acting solenoid unswitched. The solenoid is activated by switching the ground on and off at two locations, the kickdown switch and the idling switch.
Go under the car and find the kickdown switch just behind the gas pedal. Pull the 2 connector plug off of the switch, clean those contacts as they may be the culprit. Hook a continuity tester to the two prongs on the switch and push the gas pedal to the floor. The switch should make contact. If it doesn't it could just need adjustment. Go into the car and reach behind the gas pedal and push the plunger of the switch all the way in. If it now works then you must decide why the pedal isn't hitting it. The switch moves in and out by loosening the lock nut in the car and then go back under the car and put a socket wrench on the switch, it should turn in and out on threads in the floorboard. It' a good time to just unscrew it completely and clean and lube the switch and clean the threads. Then screw the switch in until when the gas pedal is fully depressed it actuates the switch.
Go under the car and with the ignition on and the car in drive and the gas pedal at least pushed halfway down as to activate the idling switch, put a jumper across the two wires in the plug you removed from the kickdown switch. The 3 position solenoid should move at this point to the forward most position. If it doesn't and you’re sure the gas pedal was depressed and the key was on it could be the linkage on the double acting solenoid is frozen or the solenoid is bad or your idling switch on the throttle body is out of whack. Try the switch first. It is a simple circuit with two switches, the kickdown and the idling switch which is located on your throttle body at the venturi control. It has two wires attached just like the kickdown switch and must not make continuity after 1200rpm and must make continuity under 1200rpm as to activate the double acting solenoid into the rear most position. You can test this by unhooking both wires and starting the car in park and hooking your tester to the two connectors and as you accelerate the motor at precisely 1200rpm the switch should open and you should not have continuity and under 1200 rpm the switch should be closed and make continuity. The switch is adjustable via two allen screws and it slides on its mount to adjust when it activates. Don't look for any voltage at either of the switches as the double acting solenoid has constant 12 volt power from fuse #3 and you are merely switching to ground with both switches you will not find power at either switch. You can test them with a test light by hooking one lead to the positive terminal on the battery and checking each switch lead for ground, one lead on each switch should have constant ground and one lead on each switch should only be grounded when the switch is activated. Also these switches work together and that is why your kickdown won't work unless the idling switch is in the open throttle position. It is a very simple circuit, 3 wires go to the double acting solenoid on top of the tranny, one from fuse #3 with 12 volt positive unswitched current, then a wire goes from the double acting solenoid to the kickdown switch and it switches the ground to activate the kickdown. The idling switch is wired to the double acting solenoid also and also switches the ground to activate the double acting solenoid. These switches work together and you must not activate them both at once, that is why you must have the gas pedal slightly depressed when testing the kickdown switch. Now the constant speed solenoid on the manifold to kick up the idle when in gear is supplied constant unswitched 12 volt positive power via fuse#5 and is activated by two oil pressure switches on the transmission each of which simply switches the ground on and off to the solenoid when the transmission fluid pressurizes the forward gear switch or the reversing switch. Remember all of these actions are activated by switching the ground and not the hot lead so looking for 12 volt positive power at any of the switches will not work. You must confirm they are actually switching the ground on and off and there are many many ways to do this depending on you equipment and personal taste. I have outlined some details here but not all, and there may be easier or better ways. Just remember, you are switching the ground on and off with constant 12 volt positive power on all the solenoids. The double acting solenoid is simply a 3 position solenoid, with the idling switch activated the solenoid moves rearward, when you go above 1200rpm the solenoid is totally off and moves in its relaxed state to the middle position and when you activate the kickdown switch it moves to the forward position."
Bob