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Dealer added cruise control - works!


In the late 70's/early 80's I installed a bunch of cruise kits and dealer installed a/c systems. Some of the cruise kits used magnets held to the driveshaft with nylon tape and a magnetic pickup bolted to the floor pan. Later the kits came with a speed sensor to plug in between the speedo head and the cable. There used to be 2 adjustments for sensitivity and centering to tailor the way it worked to the individual car.
I installed cruise on a Mercedes 190 diesel once, the most gutless car I'd ever driven, and the customer came back complaining about the cruise shutting off on hills. The car didn't have power enough to maintain speed on hills without downshifting. Cruise can't downshift a manual transmission, the car lost speed, so the cruise shut off. The owner knew he had to shift down on hills and it was still hard to explain to him why the cruise was shutting off.
 
Surging on my factory setup is always low vacuum.

At first because I had the vacuum line routed over the brake booster... which would get pinched by the hood hinge. That was fun to figure out.

I think the valves are worn in my servo. Sometimes when I hit a bump it gets to surging like a valve might get stuck in its bore. Another well placed bump or rapping on the servo with my leatherman will revive it.

I added the factory cruise in mine though, your results may vary.
 
I'm gonna wrap up this thread with just a couple more links for folks considering things:
1) dealer added NOS (this is from page 1 as well) - spark surplus

the NOS kits are $200 ish

2) Rostra, probably #1 or #2 biggest aftermarket
(although their site is confusing and just about impossible to navigate)


expect $300+

3) The Cruise Control Store:
- they are just a reseller, they sell Rostra and Dakota Digital


expect $300+

4) Take it to a dealer
expect $$$$$

5) if you are prewired (3rd gen or newer), junkyard parts and follow the guide on TRS here:


cheapest option

I've gathered that 2nd gens have 2 different wiring harnesses, those with cruise got a harness with all the cruise stuff, those without got a different body harness that has no components - so using a junkyard part collection would be a lot harder, hence I went with the dealer addon style.
 
Surging on my factory setup is always low vacuum......


I had 100% talked myself into removing the clutch switch and adding a 2nd electrical NC switch in series to deal with the clutch... so I will be eliminating the clutch switch vacuum line etc. Would you leave or remove the reservoir?
the 2nd gen factory looked like this:
1734452336426.png


the manifold line goes to the servo vac port closest to the electronics connector / more on the front of the servo.
from the side/ back of the servo out it goes to the reservoir and T connects right there also going off to the clutch switch.

The ford manual diagram in post #1 looks as if the servo only has 1 port, but this one (dealer add on) and the ones in the junkyard (factory not dealer add on) had 2 ports.. I only took a couple quick pictures of the F150 that I missed out on so am not 100% sure of it's routing and the other F150 I got the sensor donation from was chopped, the junkyard rats even buggered the wires on the speed sensor but it was the only one in the yard so I made do.


edit:
I decided to go look up every part number in the ford diagram on post #1. the "valve body assy." (part number 9c727) appears to be integrated into the servo. I only have 2 parts under the hood, the servo (which has the only electrical wires at all) and this round ball with 2 vac ports I called a "reservoir" because it has no weight, no resistance to flow (in either direction), it feels like nothing but an empty sealed ball with 2 ports.
If it's possible I misrouted the vacuum by not understanding and simply fixing the route that would be the fastest and cheapest, so I ask.
 
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Dunno if it helps or not but here is the factory diagram for my factory cruise:



I only have one reservoir. The old school looking soup can thing, I don't have much for vacuum demand, only cruise and vacuum advance on the distributor.

I started out with a check valve, in my trials with the vacuum line getting pinched I took it out and forgot about it. Not sure how much of a difference it makes.

The clutch on the factory setup is a switch. The brake has a valve that dumps all vacuum in the system. I like it, there is no chance the system will work without vacuum and if anything goes wrong it kills the system.

I have to have the vacuum feed line tucked behind the brake booster with the washer squirter hose just right.
 
Well both your diagram and the ford diagram on post #1 both agree on something that looks just goofy dumb to me, but that's just my brain I guess.....
When you hit the brakes and it lets go of the vacuum it will dump the entire system all the way to and including the manifold - that just doesn't make sense to me, but guess I don't understand what it is doing.

I routed my vacuum like the junkyard examples not following the diagram (since I didn't have part number 9c727, and my servo has 2 ports like the yard ones not like the diagram)... I am gonna go stare at it for a few minutes, try a re-route that makes the most sense and see if that fixes the surging and clutch (should have been brake) vac switch not working.
 
as far as vac demand, yeah I have a few more things, 1990... so power brakes, air cleaner box... could also have a leak, but it runs right doesn't act like it.
 
I guess I have power brakes too but it just plugs into the carb, it doesn't go to the manifold/reservoir.

My brake dump valve hose goes to the servo, mine has two ports as well.
 
well a little "playing" with the hose routing and I think I have everything all sorted out..
I routed it up as close to your diagram and the post #1 diagram as I could and the safety deadman valve (should be brake, but I have on clutch) does not work at all, it rips up to 5000+ rpm just as fast as I can grab the control lever and shut it down. BUT the surging totally leveled out and it runs like it should - very gently. (plus everytime you shift with the cruise off you hear a sucking like a vacuum cleaner was on overriding the stereo)

So with nothing to loose I moved the deadman valve to the only spot left, that one didn't make any sense, the back of the servo... works perfect.
When you depress the clutch it bumps up about 75-100 rpm then shuts down within a half a second, guessing that is just old tired servos taking a 1/4 second to trip the brain box.

But get this, after you return the deadman valve closed the cruise is still on and set and it will climb back up to the set speed. With that last fact that means I could even downshift/upshift and the cruise wont loose its place and just move back to last speed if I leave the deadman valve on the clutch.
Don't think I will move it to brake, cause to me it adds functionality (downshift without loosing cruise) and tapping the brake for a blip should shut it down, not just pause it for a second.
 
The green/brake circuit must be closed to ground or else it will not turn on. If you open that circuit it immediately turns off cruise.

Kinda sorta. Nothing outright wrong with what you've said but there's some nuance to it. If you were to wire it up as you've described and hit the brake pedal, you'd directly short the brake light circuit to ground and pop whatever fuse feeds the brake lights.

Ford speed control injects a small voltage into the BOO circuit. It is low enough that incandescent bulbs will not illuminate, and it's effectively shorted to ground through the light bulb filaments. Then, when you push the brake pedal and give it full battery voltage on the BOO circuit, the cruise module (or PCM where applicable) sees the "high" and cancels cruise.

As you noted, if that tiny voltage coming out of the module (or PCM) is not pulled down to ground, cruise will not operate. Pull it down to ground, and now cruise can operate. Put 12V onto it, and it cancels cruise.

This is, for trivia's sake, the reason why swapping period Fords to LED brake lights without the use of a resistor (even if that resistor was not required to fix turn signal flash rate) causes cruise to stop working, and in some examples, for the brake lights to be permanently illuminated. The LEDs do not provide a good path to ground for that tiny voltage out of the module, and the tiny voltage is enough to illuminate some LEDs. For my Ranger, which does not have Cruise but is running with a 93 ECM that had cruise, and my truck does have LED brake lights which were illuminated at all times by that ECM, I sent the BOO circuit through a "turn signal resistor" directly to ground in the engine bay because I found easy access to the BOO circuit there.

The vacuum dump is a secondary/safety feature. The primary way that operating the brake pedal cancels cruise is electronically through this circuit.

Information given above is all learned from playing with factory installed cruise in 83-93 Fords. Dealer installed stuff, as I understand it, works about the same way but just looks different.
 
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The dealer added does not tap into the existing brake switch, it adds a whole 2nd separate switch so it just works independently of the factory wiring.

I had to google up BOO - had not heard that acronym... Brake On/Off - that is your meaning, right?

But that raises a question, could a guy add a LED to that line and use that as an indicator that the cruise is on?
I'd prefer to have a little light (or wire in the factory light) to indicate not just cruise was on, but engaged. The dealer add has no indication at all that it is on, the switch returns to start position, there's no lights...
 
You are like 5-10 years too old for a light.

The brake switch trips something in the brain box electronically to deactivate cruise.
 
I can't even remember if the old topaz, or taurus, or even the really old buick century even had cruise much less if it was dealer add... The first car I can remember having cruise was the '92 sable (mercury version of taurus), but again can't remember if that had an indicator. None of the farm trucks had it, dad was too cheap, all the F150's F250, and the one ranger we ever had didn't have cruise. At some point, I don't even remember when I did drive one with the exact same stalk as what I have now not realizing that was dealer add, so I have seen it and used it.

And yeah that is exactly what I figured with the brake switch, it doesn't pause it and let it resume like the vac switch, and it doesn't deactivate it but leave it on (just poke resume), it shuts it OFF.
 
Mom's '94 Explorer with factory cruise didn't have a light. If anything would in RBV land I would think an Explorer would.

They were around though, my '90 Plymouth Laser/Mitsubishi Eclipse said had a light on the dash that said cruise. The switch had an amber light when cruise was turned on/armed and it had some sort of green light on the dash when it was actually set.
 
The dealer added does not tap into the existing brake switch, it adds a whole 2nd separate switch so it just works independently of the factory wiring.

Ah, missed this part. Yeah, that does somewhat change the implementation.

I had to google up BOO - had not heard that acronym... Brake On/Off - that is your meaning, right?

Correct, that is Ford lingo as used in factory service manuals, and that is how I was using it.

But that raises a question, could a guy add a LED to that line and use that as an indicator that the cruise is on?

The voltage is present at all times the key is on, so adding an LED to this circuit would not tell you what you're looking to know. IIRC there is a place that you can tap into to do something like that but I don't recall exactly where. Possibly on the wiring that goes to the servo but possibly only internally on the PCB of the module.

Mom's '94 Explorer with factory cruise didn't have a light. If anything would in RBV land I would think an Explorer would.

Yeah, Ford didn't really believe in a cruise indicator light until pretty late...maybe even until required by law or industry standard (whichever it was that caused everyone to adopt them), I'm not sure. Passenger cars, even highly optioned fancy ones, didn't have it in 2000 yet.
 

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