Cruise control...

Okay, I have a question that is sort of a mystery. My car has cruise control, BUT it is not what is shown in any of my service manuals, or the owner's manual. The transducer looks identical to what is shown, and what GM used that year, but there is where the similarity ends. My car does not have the control on the instrument panel as would be expected, and as is shown in everything that I have ever seen. It has the set button on the end of the turn signal lever, which is NOT shown in anything I have seen or read. The lever looks to be original, as the trim around the end is gray, just like the other levers in the car. Also, I have hunted high and low and found no switch to turn it on or anything. So, any ideas as to why it is so different? I would think that if it was an aftermarket type of thing, that they would have not gone to all the trouble to change the turn signal lever. And, how do you turn it on, or off? See pics below to see what I am talking about.

Pic 1, transducer. Pic 2, turn signal lever with "cruise" written on it and set button on the end (I know its not the greatest pic). Pic 3, the control that was on the '68 cars when they had the cruise option, as shown in the owner's manual and the shop manual.

some enterprising sole has put one off a later modale car on your car. it could have the flip switch to turn it on or they could have just wired it in. I'm taking it that you have tried to get it to work and it does not? just run it up to speed and push in the set? then of course you need to find the on switch of if it getting power. start at the transducer and trace the wires back. one will go to the fuse block or a fused hot source or a switch. but the transducers were known to be problem

The factory unit that you have pictured was what originally was installed at the factory. What you have in your car is what was used as a dealer installed cruise control unit. It is also known as a vacuum controlled cruise control unit. You get the car up to speed, and then push the button, and it engages and holds the speed. The electric unit that was factory installed was much more complex a unit. If you have access to a 1967 / 1968 Pontiac service manual, you will find the description in there. There is both an electrical and vacuum (mechanical) release at the break pedal. They are not very complex units to work on. What I do find strange is the way that they have the speedometer cables hooked up. It looks to me that they got the unit from another car and the cables were not long enough, and they used rubber hose to extend the casings and installed new inner wire to make up the difference. A good speedometer shop in the day would have made up custom cables for that unit, and they would look like it was factory installed. I also question why they have installed a jumper wire on the unit. More questions than answers.
Paul

if it was dealer installed there would be a on off switch to shut the unit off.

Well, I guess that answers that. Yes, I have tried to engage it at speed, but nothing happens. I will hunt for a fuse, etc. I wondered if it turned off when you touched the brake, lets hope it does, as there is no other way to turn it off! I have seen rebuilt transducers different places, I will have to try it again when I have found a fuse and see if it is bad or not. It would be nice to have it work, it is REALLY easy to speed in that car for sure. The first time I had it on the highway I was sure I was doing about 70 and was really doing 90! Whoops....

Paul Steinberg said:

What I do find strange is the way that they have the speedometer cables hooked up. It looks to me that they got the unit from another car and the cables were not long enough, and they used rubber hose to extend the casings and installed new inner wire to make up the difference. A good speedometer shop in the day would have made up custom cables for that unit, and they would look like it was factory installed. I also question why they have installed a jumper wire on the unit. More questions than answers.
Paul

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Well, you are both more than welcome to have a gander at her in Hudson and see what you think. Thanks for your input though, I appreciate it.

Another view

Here is another view of the unit, from the side showing the rubber hoses, etc.

Speed

Shawn Blyler said:

Well, I guess that answers that. Yes, I have tried to engage it at speed, but nothing happens. I will hunt for a fuse, etc. I wondered if it turned off when you touched the brake, lets hope it does, as there is no other way to turn it off! I have seen rebuilt transducers different places, I will have to try it again when I have found a fuse and see if it is bad or not. It would be nice to have it work, it is REALLY easy to speed in that car for sure. The first time I had it on the highway I was sure I was doing about 70 and was really doing 90! Whoops....

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Shawn I picked up my 1971 M-M Lifeliner in Decatur ILL. on the way home I was driving the Lifeliner Looking around at the Scenery etc and a Friend calls me on the Nextel and says you need to slow down. I said i am only going 70
He says you are going 90 mph and your Jeep only goes up to 85 mph LOL
True story

Russ

Russell Dalziel said:

Shawn I picked up my 1971 M-M Lifeliner in Decatur ILL. on the way home I was driving the Lifeliner Looking around at the Scenery etc and a Friend calls me on the Nextel and says you need to slow down. I said i am only going 70
He says you are going 90 mph and your Jeep only goes up to 85 mph LOL
True story

Russ

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I can believe that. The first time I was ever pulled over for speeding was in a black 1979 Cadillac Sedan DeVille, with dark tinted windows, white letter tires and cragars on it. I didn't even know I was speeding, that's the sad part. Incidentally, I was in Ohio at the time. Since I didn't have the money on me to pay the fine, and if I wouldn't have had my AAA card, the car would have been towed and I would have been taken back to the police station. That's what they do to out-of-staters, just a warning for everyone travelling to the meet this year. I don't know if it is still this way, as this was a long time ago. Maybe Chief Ron can let us know....or at least get us out of trouble....

John ED Renstrom said:

if it was dealer installed there would be a on off switch to shut the unit off.

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In my last post, I was going from memory, and now I have checked with my 1968 Pontiac Service Manual to make sure that what I had originally posted was correct. There is no on / off switch, except for the electric brake pedal switch and the vacuum break switch. This is all that turns the unit off, and when you push the button at the end of the directional lever shaft, it powers completes the circuit and engages the unit under the hood. Keep in mind that this was 43 years ago, long before most of the safety issues were even thought about. This was only the second year of the Federal Highway Safety Transportation Act passage. Depressing the brake pedal was all that was needed to turn it off.

Thanks Paul! I will save that picture if I am allowed to and see what I can find out next time I am poking around. I guess you have answered the question! :3_7_11v:

is the added vacuum bottle part of the system? the one this I find most challenging is removing all the stuff people have added threw the years. with that dealer add on system you would have to reset in every time you shut if off. but still better then none.
but do the simple checks make sure there is power to the system and that the shut off switches are operating correctly. your speedometer is working so what ever the reason for the rubber lines, that is not effecting the operation. but a switch out of the holder or a wire dropped off would. as would the hot wire hastily added to the fuse block. don't forget corrosion at the terminal block at the unit to. funny how crappy they can look and still work. but all it takes is one small brake in the system to shut it down.

John ED Renstrom said:

is the added vacuum bottle part of the system? ........

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Ed..... that is not a vacuum bottle, but the air compressor to power the rear air shocks. Looks like it was relocated from the back of the right hand inside fender well where Cadillac originally installed it to the other side of the engine. I don't know if this is an original or it has been replaced. The thin black plastic line that is coming out the tower with the yellow cap goes to the rear of the car and a splitter then takes it to the two rear air shocks. Sometimes they have a control valve the regulates the hight of the car and has linkage between the rear axle assembly and the body. The original compressor pumps were vacuum operated, and were quite noisy.
On some of the cars, there would be a plastic vacuum tank mounted on the firewall that is connected to the intake manifold, and the second nipple is connected to the line that goes to the cruise control head. If you look under the air cleaner, you will see a beaded chain. This chain goes to a vacuum canister that is mounted on the rear of the engine, and when vacuum is applied to it, it pulls on the chain, advancing the throttle. It is an easy system to repair if you have the manuals to properly trouble shoot it. The only finicky thing on it is the bead chain adjustment. Too tight, and it will pull too hard on the accelerator, and too loose, it will cause the engine to "hunt" for the correct speed.

Paul is right, it is the load-leveling compressor for the rear shocks. The original system had a height sensor in the rear of the car that would tell the car when it was where it was supposed to be. The compressors are easy to find rebuilt, it is the sensor that is hard to come by and I have been told didn't work that well even when new. Right now, the car just has regular, put-the-air-in-yourself air shocks.

There are two huge vacuum storage tanks on the car, located on the driver's side, one on the firewall horizontally (you can see this one in pic below) and one inside the fender vertically at the extreme right on the firewall. They look like large cans you would get coffee in.

The compressor is in it's original location, that is where they were from the factory. See pic below from an original 25,000 mile Fleetwood 75 that is currently for sale and you will see the compressor is in the same place. Incidentally, if I had the money, I would buy that car--it is cherry and has the division window and black leather chauffeurs compartment to boot.

Shawn,
Just some more information. That appears to be a 1970 and later AC cruisce control transducer. Previous to that era the transducer used was a Perfect Circle supplied unit that was much larger and more "streamlined". There were some GM cars that had a on-off switch for the cruise on the insturment panel in addition to the lever on the steering column. The dealer installed AC units in some cases had a add-on switch below the i.p., and some had the steering column lever depending on the model usage. About 1981 the cruise control had a resume feature that included a vacuum solenoid attached to the transducer.

Diesel engine vehicles had the transducer colored blue or black. What the difference was I do not know. I have seen them swapped between gas and diesel vehicles and they SEEM to work. the parts book did list them by engine usage though.

IIRC, one of the terminals to the transducer should always be hot, the other only when the switch was engaged (pushed in to set). The third terminal on that transducer was a indicator light. A lot of service transducers had three terminals on them , you just disregarded it when connecting the "T'eed" connector.

From the parts catalog at work, for up to 1975 Cadillac, dated 4-83 it shows the AC transducer usage starting in 1970. The AC and Perfect Circle were not directly interchangeable IIRC. Again, time dims memory. But hope this has been some help.

P.S., I looked for any illustrations of the Perfect Circle system, the only thing that is illustrated is a generic utilizing the AC transducer. Shop manual time.

I second that... From my understanding, the System pictured was available in 1969 on Eldorado only, and in 1970 on all models.

Very possible the AC system was in use in '69 The last printed revision of the 1975 and earlier GM parts catalogs in 1983 for all the divisions had some errors and omissions.

There was a note in them at the time that this was the last expected revision of the catalog. So a lot of them have MANY hand written notations and changes over the years.

Shawn, A couple of simple things to check that have happened to me over the years: The chain from the cruise vacuum servo (mounted typically on the rear of the intake manifold) to the throttle lever on the carburetor might have a support that the chain can slip or jump out of. Also a crack or hole in a vacuum line can disable the whole thing. I think both of these have happened in my '73 Buick Centurion convertible. I recall one night heading home the cruise suddenly stopped working. When I stopped a few miles later I found the chain out of its retainer and popped it back in using a flashlight and my fingers. A two minute fix had me cruising again! That car has an aftermarket cruise and my thought was that those beaded, keychain like chains were typical of non-factory systems. Your car is pretty heavily optioned for a F75 with auto-dim and tilt! Hope to see you and your '68 in Ohio this summer. Good luck.

John Burchfield said:

my thought was that those beaded, keychain like chains were typical of non-factory systems.

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The chain was GM's preferred method of connecting the cruise control to the carburetor for many years. It is a very simple and easy system to adjust.

Looking at that turn signal lever, it looks like Cadillac, but it can be no newer than 1976. That was the last year that the full size cars all across the GM line used a turn signal lever with a single screw attachment to the turn signal switch.

Starting in 77, it was a push/twist retaining of the lever in a pivot that facilitated the dimmer switch.