Just looked through Bentley and Haynes and they are not much help on the cruise. I don't see a ground connection in the wiring diagram. Is the ground coming from the brake pedal? what is the circuit through the stalk, mercury switch, and pedal switches? Does it provide ground to the unit or should it be hot? Is there a test for the speed sensor?

Jessie,

Just curious, have you checked the vacuum switch at the brake pedal? I know most Volvo electronics are the first suspect, but this is Dana, and the most common trouble with the '84 cruise is the vacuum leaking at the pedal. Take the hose off of the throttle actuator (vacuum motor) and test it there by making sure it holds a vacuum. Most folks find picking the brake pedal up with their toe gets the cruise working again. If this isn't it, I can find the ground for you tonight. Power comes from an inline fuse at the red/green wire at the brake lamp switch (not shown on the WDM) but derived from fuse 6 on the '84.

Hope it saves you a speeding ticket!
--
Art Benstein near Baltimore

Thanks Art. I have already checked the vacuum switch (actually I read an archived article of yours) I have blown into the hose from the actuator and there is no leakage. I have checked the stalk switches, and I get power from the brake pedal (through the switch) and from fuse #1 at the control unit. I also noticed that the ground comes from the actuator in the engine compartment.
What I don't understand is how the clutch and mercury switch work. If you hit the brake the brake switch sends a 12+ signal through the clutch switch and mercury switch to the control unit to disengage it. But what happens when you push the clutch switch without the brake? There is no 12 volt signal. The wire is connected to the brake wire going to the bulb failure relay so it must be getting a ground signal or something from that. It says something in Haynes about the cruise not working if both brake lights are burnt out. I hope it was not tied into the "ding ding" thing because I turf them out whenever I get a Volvo(the noise drives me crazy).
Anyway everything checks out otherwise. I am going to do some errands so I will see if it is working. I don't know how to check the actuator and the control unit, but I have some spares that I can try swapping in, except I don't know if they work either.

Jessie,

I see your point about the opposite effect of the brake switch providing +12 and the clutch switch interrupting either the +12 if the brake is depressed or ground if it isn't.

Looks like a clever trick by the cruise control mfr. If the input to their controller (green wire pin 13) is tri-state responsive, it could accomplish that all with one wire. If this is true, you should be able to measure some voltage above ground and less than battery at pin 13 with nothing connected. With that method Dana could read open circuit, ground and battery as three separate conditions, thereby distinguishing between clutch and brake or both signals.

But I cheat. I found the wiring diagram and with it you can trace the circuit at component level all except the guts of the controller itself. I'll scan it if you like.

Art
--
Art Benstein near Baltimore

OK, Jessie, I will try to help as soon as I can get my hands on the books, one of which, I think, was an owner's manual supplement on the cruise. Not until posting did I discover your earlier message about having one of those vehicles that develops positive pressure in the manifold! These unassisted vacuum cruises are weak enough climbing hills in normally aspirated applications without expecting them to work when you blow into it. Also, mine is an automatic, so I haven't chased down the clutch switch operation. That would be a pretty iffy design if it had to rely on the belt reminder annoyer to provide some path to ground for a signal. I guess the brake lamp filaments should suffice for that.

(1984 244 na auto 308K with cruise and center caps on the left side)
--
Art Benstein near Baltimore

Thanks for all your help Art. It is working now. When I took it out driving it didn't work at first, and then after messing with it the resume started working sort of. It would accelerate when I pressed resume and then shut down if I let it go. Then all of a sudden everthing started working. I think the actuator must have been seized up. I don't think this cruise has been operational for years. Seems to work well, but it is pretty aggressive on the acceleration.
thanks again,
Jessie