67 Camaro Cruise Control keeps Accelerating

[CamarokidRSSS]

Finally got the factory cruise control hooked up and working on our 67 however it continues to accelerate does not maintain a steady speed any suggestions?

[dutch]

I am assuming you have it hooked into a vacuum port - where and I also assume it has to be a specific type (probably ported) and not manifold vacuum, in order to work relative to engine speed and changing rpm level..
Does the AIM not display the actual pickup point at all? 

[CamarokidRSSS]

We followed the assembly manual, CC module is good, no vacuum leaks. Wondering if servo could be causing problem, seems to be hard to find if it is. When CC kicks on it accelerated like it is floored, but it turns off correctly either from the button  or the brake pedal.

[69Z28-RS]

We followed the assembly manual, CC module is good, no vacuum leaks. Wondering if servo could be causing problem, seems to be hard to find if it is. When CC kicks on it accelerated like it is floored, but it turns off correctly either from the button  or the brake pedal.

Is the actual 'speed' signal into the servo correct??  If it wasn't, then the behavior would be as stated...  Any servo is striving to achieve 'balance' between the setpoint and the actual... Any difference will drive the speed up until there is balance.

[CamarokidRSSS]

How can I verify the "speed" signal at the servo ? If this is coming from the speedometer, it is operational.

[69Z28-RS]

I have to confess, I've never owned an early camaro with cruise, nor ever had any issues with cruise on any of my later cars, thus I've never delved into them very much.  But since I was something of a 'controls engineer' for many years, I can't help but try to help you...

Someone posted a diagram on TC showing the cruise control diagram.  Apparently the speedometer cable from the transmission runs to the 'CC REGULATOR', and then to the speedometer itself.  If your speedometer is reading the correct speed, then the cable itself from the trans must be good and working into the regulator.

I'm hypothesizing here, but apparently the speed input (speedometer cable from the trans) causes the 'Regulator' to control the amount of vacuum which is fed to the servo unit itself.  The servo unit utilizes this vacuum to tug on a a chain 'pull' to increase speed (until the setpoint is reached - as set from the Cruise control).   Apparently when you 'set' the speed (the speed which you are cruising at the time), the Regulator knows this is the speed you desire (by the amount of vacuum that the engine is producing?), and either acts to speed up, or slow down, the engine speed (thru the servo) to control that level of vacuum??

I suspect your servo is working corectly since it's actuating the accelerator.  It's likely the regulator that isn't working correctly.  Since there's a mechanical aspect to the regulator (which functions based on the speedometer cable), your likely problem is there since I'm assuming you've verified all the vacuum connections and hoses per the diagram??

[CamarokidRSSS]

Hi, Actually this is on a 67, yes its the K30 option and is in the assembly manual. From what I can tell everything is correct, but hard to tell every single detail like wire colors, etc. Only 305 show they came with this option and from my searching is was a factory dealer add on.

[L78racer]

i worked in the dealer when these systems were offered on GM cars.
the problem you are describing came up from time to time.
we would remove the underhood regulator unit and send it out for repair.
i think the places that fixed the delco radios and GM speedometers were the guys who fixed them
but i'm not sure exactly where they went for repair.

[CamarokidRSSS]

While I had my car at a restoration shop where they were repairing the AC system I had them look at the cruise control he ended up replacing the regulator 2 or 3 times he kept ordering one hoping he would get one that was an exact match because I have the 2 wire which is original and he kept getting the ones that were three wire for the cruise control light so it doesn't appear it's the regulator at this point but all problems troubleshooting and diagnosis point to it and I'm not quite sure where the problem is at this point I appreciate everybody's input and suggestions it has been very helpful

[69Z28-RS]

While I had my car at a restoration shop where they were repairing the AC system I had them look at the cruise control he ended up replacing the regulator 2 or 3 times he kept ordering one hoping he would get one that was an exact match because I have the 2 wire which is original and he kept getting the ones that were three wire for the cruise control light so it doesn't appear it's the regulator at this point but all problems troubleshooting and diagnosis point to it and I'm not quite sure where the problem is at this point I appreciate everybody's input and suggestions it has been very helpful

Have you performed the adjustments as noted in the AIM in that section??

[CamarokidRSSS]

I will work on that this weekend as time allows. I downloaded the service manual as well which has beneficial information. Interesting that the servo on our car only has the one vacuum hose connection, the AIM shows it should have two. Further digging I have found both, the second is for bleed off. Now thinking it could be the problem.

[CamarokidRSSS]

More research on the servos and I found this, can anyone confirm or have any pics of a 67 servo?
"The early servo had 2 vacuum ports and the later have 1 vacuum port. 2 different servo mounting brackets were used. "

[bc69]

I have a original working K30 cruise on my 67.
It does have a 2 hose servo.