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Cruise control principle for 1981 Suburban

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MarcelSub

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Hello.
I have a 1981 Suburban with big block.
The car has cruise control but it doesnt work.
Does anyone have schematics or explanation on how the cruise control works / should work ?
Any info is welcome.

Many thanks,
Regards Marcel
 
That cruise control uses a transducer run by the speedometer cable. It is mounted on the driver's inner fender.
There will be vacuum hoses, vacuum source, vacuum to throttle actuator at/near carb, vacuum to brake switch, under dash.
So if all the components are there, the vacuum lines might be leaking, disconnected or routed wrong.
The transducers we're always troublesome. Even in the the late 80 it was hard to find a new one in the US even as a GM tech. Rebuilts were always a crap shoot. I haven't tried to get one since the 90's, So someone might be making or repairing.
My 77 had that style cruise control, I deleted it.
 
If you can't find a way to fix that old style, it should be pretty easy to swap to the later (my '83 didn't use a transducer) style, and apparently even the electric cruise control (no vacuum) stuff off of vehicles like the S10 will work.

You'd need the parts off a squarebody truck that ran VSS (1982-89) to include the cluster housing IIRC, but it really wouldn't be terribly tough.

I like cruise control, so to me it was worth the effort to run it. Up to you to decide the amount of work you are willing to do to get it running.
 
dyeager535 said:
If you can't find a way to fix that old style, it should be pretty easy to swap to the later (my '83 didn't use a transducer) style, and apparently even the electric cruise control (no vacuum) stuff off of vehicles like the S10 will work.

You'd need the parts off a squarebody truck that ran VSS (1982-89) to include the cluster housing IIRC, but it really wouldn't be terribly tough.

I like cruise control, so to me it was worth the effort to run it. Up to you to decide the amount of work you are willing to do to get it running.
Click to expand...
Good morning.

Thanks for the replies.


If somebody has a schematic that would make my search a lot more easy.
I have put 12V on the transducer, on the connector marked hold and on the valve that is next to the transducer.
Both seem to work.
The vacuum actuator on the trottle seems to be working, if i suck the vacuum line the trottle moves nicely.
I need to check the vacuum lines to the brake pedal, didn't know that it works by vacuum.
The throttle has a electrical connection, which looks like a liniair potentiometer. (didn't check yet how / if it works)
Next step would be to check the actual cruise control lever / button on the steering colum, but i couldn't figure out (yet)
how to open / remove that.

Like i said, if anybody has a schematic, that would help a lot.

Regards,
Marcel
 
MarcelSub said:
Good morning.

Thanks for the replies.


If somebody has a schematic that would make my search a lot more easy.
I have put 12V on the transducer, on the connector marked hold and on the valve that is next to the transducer.
Both seem to work.
The vacuum actuator on the trottle seems to be working, if i suck the vacuum line the trottle moves nicely.
I need to check the vacuum lines to the brake pedal, didn't know that it works by vacuum.
The throttle has a electrical connection, which looks like a liniair potentiometer. (didn't check yet how / if it works)
Next step would be to check the actual cruise control lever / button on the steering colum, but i couldn't figure out (yet)
how to open / remove that.

Like i said, if anybody has a schematic, that would help a lot.

Regards,
Marcel
Click to expand...
Should be able to download the proper manuals for your year here: http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1

Both service and electrical may be needed, but as relatively simple as the cruise circuit is, you may be able to get by with just the service manual. Just depends how in depth it gets. But they are free, not a bad idea to have both. :)

Forget Chilton or Haynes, their stuff is utter garbage.
 
The switch stalk in steering column just pulls out. The wiring goes down the inside of column and connects under dash. Iirc it 3 or 4 wires small gauge.
Also I think this cruise won't set until a certain speed is reached. I want to say 40 mph, but it may be as low 35.
 
I looked in the manuals, there is some usefull info there, only the schematics are not really 100% readable.
But its a good starting point anyway.
Will see how far i can get
 
The scanned page is not a good quality, so the markings like color etc. are a little bit of a guess sometimes...
But I think i figured it out.

I managed to test everything,
I found out that all components work,
the issue is in a bad contact in the set-switch on the steering colom.
The slide button is the problem, but if i push it down in a certain way and then activate the Cruisecontrol it works.!!

So only now i need to figure out how i can pull out the switch, to see if I can fix it.
Anybody know how ?

I will check the manuals also for that, but i think it is not in there.
I got the push button off, took the housing that holds the slide button, but now it looks like i cant get the switch out...

To be continued...
 
the whole turn signal stock come out. I don't think the stalk is repair able at least not easily.
 
Yep, stalk pulls straight out of the column. But far more work to get the wiring out of the column as it's an assembly. I assume you can damage the wires on removal as it takes a bit of force to yank the stalk out, when it lets go your hand tends to keep going lol.

It's possible to use the later setups (S10 etc) which have a wire connector at the stalk end, so you don't have to fish the wires up the column to replace the stalk again.
 
Ok, but does anybody know how to get the internals out of the black housing ?
I guess they have to go out through the side of the push button, but there is a 'star-shape' piece of plastic covering the hole, and it looks like that is one piece with the housing ....
If i can get that out i might be able to repair it without removing the wires...
 
You are talking about taking the stalk itself apart?

I've never attempted that. I didn't see anything in a quick search online about that either, just replacing it.

Not sure what your vintage looks like, but the later ones I assume the rotating end portion is clipped on with plastic fingers, getting that off would probably shed some light on how the rest of it is put together.
 
Does the end of that come off? It looks like there might be a seam for an end cap/push button.
 
I can remove the push button, the cap with the writing on it and the first (sliding) part of the sliding button...
The internal part of the switch i cant get out...
It is quite difficult to past a picture as i am not a premium member, otherwise i could show it more easy...
 
Hmm. Probably not much help then. Can you force the wiring up into the stalk? Maybe that's holding things up?

I'd like to see pics as well, never seen one apart before.
 
Yes gm considered a non serviceable part and would pay to replace the whole assembly under warranty. So I have never tried to repair one either.
 
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