If I want cruise control...

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zxr250cc
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If I want cruise control...

Post by zxr250cc » Tue Jun 23, 2020 8:59 pm

Hi all,

I have been thinking of buying an 88 T-bird auto computer to control the Scorpio A4LD I am getting ready to rebuild and install. With that being so, I am wondering what other specific parts are needed from the later XR to make it use cruise control as I believe that the T-bird ECM has that added function, in part, in it. I tried to use an aftermarket cruise control on my '86 when it was new and it worked poorly and was given up.

Anyone in here do this? A list of the parts would be great to study. Any help would be greatly appreciated.

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1986 XR4Ti Mineral Blue Metallic

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Re: If I want cruise control...

Post by merkurdriver » Wed Jun 24, 2020 3:54 am

If its a Scorpio A4LD then its not computer controlled.
Thats the beauty of using the Scorpio A4LD in an XR. . . its not computer controlled.

You can easily use factory XR cruise control stuff on your non-crusie control XR. Its pre-wired for it, you just plug the CC sub harness into a dangling plug by the steering wheel and the speed sensor fits between the speedometer cable and the speedometer head.

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Re: If I want cruise control...

Post by zxr250cc » Wed Jun 24, 2020 7:11 am

Hi, thanks for the reply.

I thought the T-bird computer controls the lock up for the A4LD. No? I know the XR ECM is completely unaware of the transmission functions.

The '86 cars also have the connections for cruise control? I asked to have cruise control when I bought the car in Dallas and they said it was coming in the future. (Terrible dealer, lousy, lousy service) The cruise control is partly in the ECM also? Or fully separate if you find the parts? What parts do I need to find besides the switch on the dash? There must be an actuator of some sort and a module or two doing other things? Is it vacuum based or rpm based? Does anyone in here have a running version of the stock cruise control?

Well, enough questions for one posting.

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Re: If I want cruise control...

Post by eaton53 » Wed Jun 24, 2020 12:47 pm

I had one of those aftermarket cruises on my '85.
It sat on top of the steering column. Worked by reading voltage. It was really easy to install too.
The downside of reading voltage is that any RPM change screwed it up. If you changed gears you had to reset it.

But as long as you stayed in 5th, it was all good. It did a pretty good job of maintaining the set speed.

Now if you REALLY wanna do it up right, Jeff has this:
http://merkurmidwest.com/catalog/i467.html
Not cheap and I have no idea what it looks like. Then again, you might be in that deep by the time you buy all of the separate parts.
At least there would be no guesswork with that kit. It's got directions and everything!

Jeff had a unobtainium NOS cruise stalk when I was in his shop a few years back.
I asked him how much and it was a similar sum which actually means "I don't really want to sell it".
That was for just the stalk, nothing else.

I have a used one that I got from Mike that's not as pretty but is holding up very well.
You can't say fairer than that when it comes to these wimpy stalks.
Mark Copeland - I'm 50 miles west of Kewanee, IL

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Car was the 2014 MCA Merkur Preservation Award Winner
Proud member of the Iowa-Illinois Merkur Owner's Association since 2015. :cheers

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Re: If I want cruise control...

Post by andyofcolumbusmerkur » Wed Jun 24, 2020 2:14 pm

Cruise control stalk with the "set" button on the end, but you could wire a switch instead. The cable and ball looking thing that is under the hood and connects to the throttle body. The switch near the fog light switch replaces one of the blank covers but you could wire a different switch. The two piece style speedo cable with the little wire that is near the firewall, but you could get something else that made a square sign wave like used for an after market speedo. Some little box with a bunch of wires and plug harness that is back behind the fog light switch left of the steering wheel. And maybe something that connects that ball to the tree or some other place for vacuum, shouldn't be hard to make that work with a check valve and vacuum hose. Probably something that releases vacuum when you press the brake pedal down, kinda like the hvac control, to stop the cruise if you are trying to stop the car.
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Re: If I want cruise control...

Post by zxr250cc » Wed Jun 24, 2020 9:49 pm

Hi all,

I remember someone in here converting a wiper stalk by rewiring the squirt button, I think, to do the cruise control. Two or three years ago. I am sure the complete Ford kit would be nice but an intercooler would be more likely than that complete set in my present budget. I must say I had no idea it was as much as that.

I had a vacuum based aftermarket unit and it was only fair and after a while tried to create a vacuum problem so I disconnected it. It is still on the car, it is just not hooked up. It used a little pull chain design to control the throttle and looked at the brake light switch for turn off signal. I seem to remember it needing to connect to one of the leads for the coil also. That design was generic and common in the '80's I think. When first installed in the car it was OK but maybe easier to deal with an auto than a five speed for that type of add on. I am sure the Ford set would be better.

Thanks all,

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Re: If I want cruise control...

Post by merkurdriver » Thu Jun 25, 2020 2:56 am

Turbo Coupe computer will control lock/unlock for the converter on the A4LD if you want it to I suppose. But you don't need it to if your A4LD is Scorpio flavored.

Also, nowhere in the XR engine computer is there anything for cruise control. It has its own separate little computer module that tucks in over by the dash speaker on the driver's side. All cars are pre wired for cruise , and by pre wired... I mean there is one dangling plug in the car that you plug the CC wiring sub harness into. Plug and play set up.

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Re: If I want cruise control...

Post by eaton53 » Thu Jun 25, 2020 11:10 am

zxr250cc wrote:
Wed Jun 24, 2020 9:49 pm
I am sure the complete Ford kit would be nice but an intercooler would be more likely than that complete set in my present budget. I must say I had no idea it was as much as that.
It's expensive because it's an unmolested NOS factory unit. Everything gonna be there.
Mark Copeland - I'm 50 miles west of Kewanee, IL

'89 XR4Ti
Car was the 2014 MCA Merkur Preservation Award Winner
Proud member of the Iowa-Illinois Merkur Owner's Association since 2015. :cheers

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Re: If I want cruise control...

Post by Ed Lijewski » Thu Jun 25, 2020 12:53 pm

merkurdriver wrote:
Thu Jun 25, 2020 2:56 am
I mean there is one dangling plug in the car that you plug the CC wiring sub harness into. Plug and play set up.
So where does the dangling plug derive from?

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Re: If I want cruise control...

Post by merkurdriver » Fri Jun 26, 2020 2:58 am

Ed Lijewski wrote:
Thu Jun 25, 2020 12:53 pm
merkurdriver wrote:
Thu Jun 25, 2020 2:56 am
I mean there is one dangling plug in the car that you plug the CC wiring sub harness into. Plug and play set up.
So where does the dangling plug derive from?

YMMV
Its behind the speedometer and to the left if I remember correctly.

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Re: If I want cruise control...

Post by Ed Lijewski » Fri Jun 26, 2020 6:11 am

merkurdriver wrote:
Fri Jun 26, 2020 2:58 am
Ed Lijewski wrote:
Thu Jun 25, 2020 12:53 pm
merkurdriver wrote:
Thu Jun 25, 2020 2:56 am
I mean there is one dangling plug in the car that you plug the CC wiring sub harness into. Plug and play set up.
So where does the dangling plug derive from?

YMMV
Thanks. I was trying to ask what do you assume that wire originates from? IOW, if one added the CC harness to it, what circuit/what part(s) already on the car is being connected?

YMMV

Its behind the speedometer and to the left if I remember correctly.
Last edited by Ed Lijewski on Sat Jun 27, 2020 6:36 am, edited 1 time in total.
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Re: If I want cruise control...

Post by andyofcolumbusmerkur » Fri Jun 26, 2020 3:27 pm

I'm thinking it "orugunates" from main bus bar postive, to power up the little module box, and maybe even a signal from the brake light switch to stop the cruise if you tap the brakes. But what if you push down on the clutch? I've seen cars with the little switch that touches the clutch pedal arm or linkage and that switch releases the vacuum. But don't remember ever seeing this on my car when I removed the cc. Or what was left of it.
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Re: If I want cruise control...

Post by merkurdriver » Sat Jun 27, 2020 2:49 am

What Andy said. I believe its just a simple plug providing power and common grounds for the CC sub harness to plug into so there is power supply for the CC computer module, switches, etc.

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Re: If I want cruise control...

Post by zxr250cc » Sun Jun 28, 2020 8:04 am

Hi all,

I had been thinking of the Tbird auto computer as it controlled the A4LD lock up, it has a setting to always use premium and I wondered if it had some function for the cruise plus it is set for an intercooler which I am wanting to install later. So three out of four still good reasons to use one.

Thanks for all the comments. As there is no photo of that system i still wonder if there is not some physical part out at the throttle body to control the throttle like the generic unit I have left over from the 80's? Is the computer doing all the speed control like modern cruise designs with an actuator of some sort?

Well, this was something that would be nice to have for long trips. It will fall down my list of wanted items to a much lower position at this time though with that price tag. Larger wheels, better brakes and an intercooler will move ahead of that.

Cheers
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Re: If I want cruise control...

Post by merkurdriver » Tue Jun 30, 2020 1:52 am

zxr250cc wrote:
Sun Jun 28, 2020 8:04 am

I had been thinking of the Tbird auto computer as it controlled the A4LD lock up, it has a setting to always use premium and I wondered if it had some function for the cruise
The Turbo Coupe fuel switch for premuim has nothing to do wth CC. Just flips the ECU over to the hotter ignition timing/fuel tables.

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