cruise control diagram

[vmrod]

I want to get my cruise control functioning again on my 1977 vette. (It never worked when I bought it.) I know that I have to attach 2 cable to it (speedo from xmssion and speedo to gauge). This I can figure out for myself.

I need to know, what vacuum lines go where? I assume that a vacuum supply is needed. (Does it come from the manifold, the vacuum resovoir or carbeurator vacuum, or does it matter?) Where does the vacuum supply plug into the transducer?

I suppose a vacuum output connects to the vacuum canister that operates the little chain which in turns pulls on the throttle linkage. Where does it connect on the transducer?

Finally, I assume that the transducer must get a signal from the cruise control 'setpoint' button on the steering column. Is this signal a vacuum signal, or is it an electrical signal? (where on the transducer does it plug into?) I suppose if it utilizes an electrical signal, then a power feed must be run to the transducer as well. (If so, where does it connect to?)

A simple diagram would help. My car is not really original, so I do not need exact procedures. (example...plug blue hose into this...) Instead a general 'howto' would be beneficial. (example...vacuum reservoir plugs into transducer top hole...etc.)

-Vic

[Bob Chadwick]

Vmrod,

You have more recent pictures of your not quite stock 77 convertible?

I don't really have any info to share with you but would request that keep this post up to speed on what you did to repair or figured out on how it works as I need to take a look at mine as well.

Thanks.

Bob

[chevyaddict]

Me too! My cc doesn't work either and would like to get it going so I want updates as well!!

[vmrod]

I'll start looking hard at the transducer today. I bet I can figure it out, if I try hard enough. I believe I fixed my headlight problems for the past 8 years, after reading a bit from the forums, and then using some common sense.

[topless82vette]

if a 82 has the same setup I can look at mine for you

[vmrod]

I don't know if it is the same or not, but I would appreciate it. If anything, it will help me to figure it out. After I'm done, I'll make a diagram and post it. It really can't be that difficult.

[topless82vette]

vmrod

if its easier for you, you can call me

[vmrod]

I may do that. I found a pic of a connection diagram from www.docrebuild.com This may help me out a good bit. If I refer to my repair manual (which does not contain any cruise control vacuum hoses), I may find if there are any wires landing on the transducer. If I can't figure it out by the weekend, I'll give ya a call and you can descibe to me what you have.

[topless82vette]

ok you have to bear with me as I describe mine since I dont have a scanner right now but here goes it ...... on top of the speedo transducer theres a round solonoid looking thing with a T vacumm fitting, the port that comes straight out goes to intake vacuum, the other fitting will have a vacuum line that goes to the front side of the bottom part of the modulator (the port thats closest to the fender) ....theres another port right beside this one it will go to a vacuum tree looking thing with 4 ports .... a vacuum line from this tree will also go to a port on the very bottom of the modulator on its side (very hard to see the port but its there) ... another vacuum line off this tree will go to the cruise servo ( the thingy that pulls the cruise cable) .... another vacuum line from this tree will go into the firewall along with 3 wires from the cruise system (probably to the brake pedal switch)

sorry no vacuum lines were color coded, my cruise works so this is a good starting point

[vmrod]

Cool! I will make a sketch (as best as I can) of your desciptions. I'll compare it to this pseudo-diagram that I just printed out, then compare it to the mess under my hood. I also have to check for the wires too. I'll let ya know tomorrow how it turns out.

[vmrod]

Hey hey!
I took the 2 diagrams home yesterday, and looked under the hood. Besides needing new speedo cables (I just have 1 cable that goes straight to my speedo gauge), all I need is to install a vacuum hose from the 4-port tree to the vacuum servo (the part with the ball and chain).
I am going to make a good sketch today, convert it to .PDF, then post it. I could make the sketch today, but I don't remember exactly where the black and white wire land. (One lands one 'HOLD', the other on 'ENGAGE'. Anyway, I want it totally correct for any one else out there. I'll also put up my headlight vacuum diagram too.
Thanks for all the help!
-Vic

[vmrod]

Allright people! I am not a certified mechanic, but I think that this diagram is correct. Please let me know if something is wrong here. (see attached zipped file for .PDF diagram)

[Bob Chadwick]

Vick,

Thanks for the diagram. I took a quick look at one of the rest stops on the Stars and Stripes tour yesterday and using the diagram found one of the vacuum lines off and the chain broken.

Bob

[Bob Chadwick]

Vic,

Using your excellent diagram I was able to finish troubleshooting my cruise control and have it working for this weekend's drive to and from Bowling Green.

Thanks.

Bob

[vmrod]

Great!! Well, now I'm sure it's correct! Hopefully, I'll be able to get mine working one day. (but you know my loooong priority list!)

You are free to put the diagram on your web-site if you want. I do not mind anyone using any information I provide here. I just ask that it is always free for everyone.