Need help with cruisecontrol 67 Electra

[jannelu]

I have some problems with the cruisecontrol on my 1967 Electra convertible.

When i engage it, it work fine and its keeping the speed ok.

I noticed that if i as an example, set speed for 60 mph it will keep that speed, but if i increase speed for a overtake etc and then take my foot away from the accelerator pedal it wont hold the speed any longer.

If i then switch it off and try to switch it on again at lets say 30 mph and with the cruisecontrol needle still at 60mph, the engage lamp will start to glow but no engagement...

As i understand it should engage just 3 or 4 mph under the selected speed and it usually does, but not always.

Anyone have some ideas about this??

Can it be a vacuum problem or as i suspect a faulty speedometer??

[NTX5467]

You have two different functions you are talking about.

The extra needle on the speedometer is for the Speed Minder buzzer that alerts you when you exceed the speed you have the needle set at. That's all it does. There is a knob to move the needle to different speeds.

Otherwise, GM's cruise controls (as well as Chrysler and Ford systems of that general vintage) have a miminum "set" or "cut-in" speed of about 30mph. Therefore, it is not designed to operate below that speed. Depending on how your particular cruise transducer is calibrated, it could well be 35mph before it will set and hold that speed.

When you do set the cruise, it should lock in on the speed that you pushed the "Engage" button and hold it within about 2 mph. Sometimes, they will briefly accelerate for a second or two as the transducer gets its activity sorted out, but if correctly adjusted they should engage smoothly and accurately. In other cases, it might let the vehicle's speed drop a few mph or gain a few mph when it sets. I'd recommend you just adjust your procedures to compensate for that situation.

I'm not sure what the glowing light situation might mean, but it probably would be good to check the wiring to the transducer and the related connections in that harness.

In those GM systems back then and up until the early '80s, the speedometer cable goes into the cruise transducer mounted on the lh front fender apron. A speedometer cable attaches to the output side of the transducer and then goes to the speedometer. There are some vacuum lines that connect to the transducer from the intake manifold and the other one goes to the cruise servo vacuum diaphragm that mounts near the back of the engine block. The cruise servo runs a linkage of some sort of a ball chain to pull the carb linkage and override the foot throttle during normal operation, but the foot throttle can override the cruise in the case of needed acceleration.

With respect to the cruise transducers, there are 2 wire models and 3 wire models. 3 wire models have an extra wire to run the indicator lamp on the instrument panel when the system is engaged. Otherwise, they are the same unit.

When GM went to the "memory cruise" version, they added mounting holes for a vacuum chopper solenoid that would mount to the bottom of the transducer. The turn signal levers for these cruises had the slide lever with "OFF", "ON", and "RESUME" in that order. Those transducers can be substituted for the earlier models, as I recall, but without the extra solenoid attached.

Under the instrument panel, there should be what looks like a brake light switch, but also has a vacuum line attached to it. It is part of the vacuum line source for the transducer to do its functions.

If, by chance you have one of the Dana/Perfect Circle cruise units from the middle '60s as factory equipment, there should be some sort of speed dial that you can engage the unit (again, at about 30-35mph) and then roll the dial to the desired speed setting. Instead of the vacuum actuation of the later models, there should be a stepper motor and a solid linkage to the carb. Any override functions will be internal with the stepper motor unit. This system should be similar to what Chrysler used until '67 and on some Fords also. Good, solid electrical connections are necessary.

With this type of system, there is no "RESUME" function. If you're at the speed where it will set, you get it to engage there and then move the setting up to where you want it to be without any action with the accelerator pedal. The cruise setting can be moved downward in a similar fashion.

It's also necessary to make sure the speedometer cables into and out of the cruise unit are in good shape and lubricated. On the later versions, if the transducer locks up, things come to a halt real quick with that lower cable and will damage the speedometer gear and the cable end where it indexes with the speedometer driven gear. With the main speed reference signal gone, the cruise should shut down and the speedometer needle go to zero while you're driving.

In the case of the speedometer, it's just a meter that registers speed and should have no bearing on what the cruise control does or does not do. The Speed Minder buzzer probably uses a simple contact switch on the back of the speedometer unit, but should not affect how the speedometer operates.

I mention both of these types of cruise controls as I'm not sure which system your vehicle has. My '68 Buick Service Manual shows the vacuum system I mentioned first, but with switches on the instrument panel instead of using the turn signal lever as later versions did. It appears the instrument panel switches operate the same as the later turn signal lever switches do, though, with respect to "SET" and "COAST" features--plus having the indicator lamp.

I hope this information helps.

NTX5467

[rocketraider]

First we need to establish which Cruise Control you have. From my knowledge, these cars could have had: the Dana/Perfect Circle all electric unit; AC vacuum transducer unit; or AC vacuum/electronic Electro Cruise. All three work differently. Since you say there's a speed set needle and an "engaged" lamp on the speedometer, this sounds like Electro Cruise. Complicated system, and not easy to service. A problem like this is generally in the electronic box on the back of the speedometer head.

My guess is you'd have to find an AC authorised speedometer repair shop and hope they haven't obsoleted all the parts. Pontiac also used Electro Cruise 1964-67 but it's rare.

[Philippe Racicot]

Rocketraider is right: 67 Electras, Wildcats and Le Sabres 400 (with 400 transmissions) uses Electro-Cruise wich is much more complicated than the vacuum transducer used on 68 and later Buicks (the system that NTX5467 explains).The Electro-Cruise unlike the later type does use a speed pointer just like the cars with "speed alert". When it works correctly it is supposed to be accurate and it should engage to the set speed. My 67 shop manual explains your system and as soon as I have the time I'll try to find possible causes in the troubleshooting section.

[rocketraider]

Philippe, I'd like to get some of that troubleshooting guide too. A buddy has a 64 Grand Prix with a non-functioning Electro-Cruise that we're trying to get working, and the 64 Pontiac manual is vague at best on this system. We've accumulated some parts including a hell of a find at this year's Spring Carlisle- a complete NOS 1964 setup. Installing it will be part of this winter's projects. Shame to replace the whole works though if replacing one or two components can solve the problem.

[jannelu]

On my car it is a electrocruise, i have changed the whole speedometer as the old cruisecontrol units oscillator spring was burned off due to a electrical short(my own fault)

I have also checked the transistor and amplifier and everything seems to be okay.

I have also cleaned and checked the vacuum unit.

But i still have problem if i speed up the car faster than the speed setting pointer, it wont engage when the speed is decreasing below the speedo setting pointer even though the engage lamp is on.

If i dont exceed the speed i have selected it works just fine.

I suppose that`s a problem with the oscillator spring in the new unit as well.

I will take it apart when winter arrive, its a lot of work just to remove it from the dash so i dont look forward to do it all again...

Thanks for your tips and ideas..

[NTX5467]

Is the complete setup you purchased an GM Accessories factory kit or the pieces from the production option? There could be some differences.

The Chrysler unit I mentioned was circa '67 and prior. There was a dial on the instsrument panel with some sort of "ON" switch in it. Once engaged, you rolled the dial (with reference numbers on it) to the desired speed (above about 30 mph) and could vary the speed with the dial. On some, there was a small set screw adjustment so you could adjust the numbers to approximate the mph on the speedometer.

The control box was mounted on the lh inner fender skirt with linkage to the carb from there. Pretty much self-contained.

In the '80s, I orchestrated a deal for a friend to purchase the obsolete parts from an old dealership a work associate had bought. In that "stash" was a factory cruise kit for a '65 or '66 Impala. It was the same type as the one Chrysler used--except it mounted the control box on the core support by the radiator. Naturally, the speedometer cables were very long. It worked the carb with a long rod that approached from the front instead of from the rear. Quite a bizarre setup! I wanted it to possibly adapt to my '66 Chrysler, but when I saw how unusual it was, I halted that idea. I don't know if I would have put it on anything as explaining what it was would have been more hassle than it was worth, even though it was a factory Chevrolet accessory item.

On the system on the Buicks back then, I suspect the concept of how they operated compared to the Chrysler unit is similar as the control box "guts" would most probably be the same. The switches and how they operated the control box would vary. Chrysler used one integrated switch where it appears that Buick and other GM lines used a couple of different ones. I suspect troubleshooting would be similar in concept to the Chrysler systems also, but Chrysler never used a speed buzzer or extra needles on their speedometers.

In one respect, it can all boil down to having good electrical contacts in the wiring harness, in the switches, and inside the control box (i.e., contact points as in a clock, I suspect). As with a clock, the contact points could be gummed up with age and environmental exposure and grease residue. Cleaning them might be all that is needed as the basic calibration would not have changed over the years, typically.

Good luck with your project.

NTX5467

[rocketraider]

The kit included: speedometer head with 00000.0 miles which incorporates the on-off switch, speed sensor and feedback; brake pedal disengage switch; amplifier that mounts to back of speedo cluster; vacuum transducer/diaphram that bolts to the firewall; and all associated wiring, vacuum hoses and mechanical linkages. All in a "Pontiac Factory Engineered and Approved Accessories" box labeled "Electro Cruise Control- 1964 P8" which is 60s Pontiac-ese for a full size car.

NTX, I think you still haven't grasped Electro Cruise. It was a vacuum-electronic system. The speed sensor was incorporated into the speedometer head itself, no transducer or governor. The electronic signal it generated went thru an amplifier mounted to the back of the speedo. The amp sent a signal to a small transducer incorporated into the throttle linkage vacuum diaphram, which converted the electric signal to vacuum and operated the diaphram. It was switched on using a knob in the speedometer which lit a "CRUISE" or "ENGAGED" lamp and also moved the speed set needle to your desired speed. Once speedometer hit desired set speed, E-C would engage and maintain speed until it was either manually switched off or disengaged by brake application.

Simple enuff, right? until you have to remove the speedometer and half the dash to service the thing, and nowadays find someone who can work on it and hopefully have parts to fix it .

[NTX5467]

Thanks for the information and updates. Sounds quite a bit more complicated than the Chevy kit I had or the Chrysler units. That was back when each GM division pretty much did their own thing, also.

One reason the Pontiac service manual might be a little vague on it could be that there was a separate manual specifically for that set-up? Just a thought.

Enjoy!

NTX5467