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Where's that !!@&$^#*!ing RELAY for cruise


Motor head!!!!
Feb 13, 2001
Valencia, CA,USA
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
C4 C5 where are you when I need you???

Ok Ive dug all over and cannot find the mystery cruise control relay... In the front, by the Vac canister.Could you take a picture or draw a map etc?

Keep in mind that the front end ( body work ) has been replaced on my car ( "updated" )

but the more I dig around I find signs that it was involved in a slight bender, however there has been some less than creative wiring done, which I have cleaned up.

The colors and pin #'s would be a help too!
There is NO listing of it in the GM manual
or Haynes

I think this is another GM Oh by the Way....

Hi there,
Well, I am interested in this one. What exactly is the issue with your car??
I might have missed another post on this. Wiring from the cruise control stalk to the brake switch to the instrument cluster.
Fron there, it goes to the servo, and then back.
I need more information here please.
best to you, c4c5
The past info

This is your posting correct? We had a discussion about this relay ( controller ) so I could get my cruise working...I'm still searching fir this item so I can check it... to get my cruise working

Registered: Jun 2001
Posts: 6
Location: Whitehouse, Ohio
Corvette Ownership
85 red coupe

Cruise...the module that controls the cruise is in the front drivers side in front of the
wheel under the headlight, lift the hood and you will find it on the wall near the ball
shaped vacuum canister. I would also check the fuses...now another thing I found was the vacuum lines. From the canister there is a vacuum line that goes to the cruise control and then tee's off to the TPI plenum on the passenger side rear just in front of the distributor.There you will
find 2 vac supply ports, the front one goes to the egr control relay, the one in the rear
goes to the cruise control and supplies the interior a/c and heating ducting. connected
to the rear port is a cruise control check valve. The cruise control and interior vac line is
connected to this check valve. If this valve is bad, your interior a/c and heat controls
will not work, you will not be able to control the direction of air inside, air comes out of
everything all at once, the cruise control will malfunction as well. Check all the vac lines
for breakage especially where the connect. The air conditioning also has fuses and check the connector on the compressor. Plus there just so happenes to be an a/c power control relay. I have searched all three manuals and none show where it is
supposed to be. Wish I could be of more help...take care and good luck...
Nope, but to continue

I msorry, however, this was not me that posted this.
Anyway, according to my books, there is not a relay that I am aware of.
I would recheck diagnostics, and talk with the person who posted that information.
Let me know if I can hhelp further, c4c5
Sorry it was Eagle 85 c4

Oops wrong guy!
Eagle stated the following
That there is a relay by the Vac casnister that was part of the cruise control circut.

Now I've checked everything I could and everything seems ok but Eagle is sure that there is a relay there... I cant find it. nor is it in the GM shop manual, nor listed in the electrical supplement
on in the haynes manual.... So I guess back to square 1

Lets start from square one.

Hi there,
Lets start from square one.
The first thing that I would check is the brake switch, located in front of the brake pedal, which has a light blue wire and a gray wire with a black tracer. This switch should be adjusted to the stop on the brake pedal. If it is not, this will not allow the cruise to engage, as it sees that the brakes are on.
This is a sliding pin, which when pushed forward, will bottom on the pedal. Force it forward, then, pull back on the brake pedal with 2 fingers, you may or may not hear it ratchet back.
this is your first course of action.
Let me know how you do, c4c5
vigman said:
...cannot find the mystery cruise control relay

Hey Mike, I was just going through Gordon Killebrew's book and there is no mention of a relay for the cruise control (K34).

If its not functioning, maybe its the fuse.
I never referred to it as a relay, however, I did in fact call it the cruise control module. Refer th the post help with a/c and heating.
Page 6-12 of the Chiltons manual for Corvette 84-96 and you can read the explaination of this. Page 4-30 shows a good picture of what I am being told is the module just to the right of the vac cannisterjust in front of the drivers side front tire. A good schematic is found in the Haynes manualCorvette 84-96 0n page 12-29. And it clearly shows the cruise control module. And in the Clymer Manual for Corvettes on page 143 it shows a breakdown of the wheel well in front of the drivers side front wheel, and it points to the cruise control module.
Now I am not saying these are right, just what I have been shown so far. If it helps great! If not , sorry i tried....
Eagle, rock on

If I may, whereas we all make mistakes, just keep working at it. There is not a sin in making mistakes, and we all are here to work together to a common good, the care of Corvette.
Best to you, c4c5
I don't believe I made a mistake, all I did was introduce information from widely published manuals for Corvettes.
In the short time I have been coming to this sight, I have been called a liar...told I make mistakes and told I don't know what I am talking about when it comes to auto a/c. And I am an engineer with certification in all arena's related to the freon and refrigerant field. You know maybe I did make a mistake...coming to this corvette community. Thanks but no thanks....there has got to be a better place...this is the weakest link....goodbye!

I've been following this thread, but I have to disagree with you. I don't see anyone here calling you a liar. What I do see here is some confusion among everyone about whether or not we're talking about a relay or a module. Unless you've received private messages from someone, I don't see anyone here telling you that you don't know what you're talking about. Is there something that I'm not seeing or am unaware of here?:confused
I had an 86 coup with cruise problems. I found the pin-outs for the dash cluster on the web and traced the connections from the stalk directly to the cluster. I have a print of that information that I can retreive if you need it. I do not believe there is a relay. BTW, my problem was in the stalk. The contact had broken off from the coast/set button and was sending a constant coast signal even though the button felt like it was working.

86 coup (gone)
96 Grand Sport

Hey Eagle,

If I have offended I am sorry....
I was confused... and asked more questions and got more ( varied ) answers! And you are correct I called it a relay ( for lack of proper description of function by the GM books) I will look at the Books & chapters you note.

Obviously none of us were in on the original design of the C-4 (and all it's iterations) and in My opinion the cruise control is not a great design, and the documentation is abstract at best.

Isn't that how we learn?
By inquiring...experiencing...and streamlining.

I am thankful for the advise I recieve here, and in turn I try ( whenever possible ) to return in fashion.

So thanks all of you for your support!

Re: Wow.....

vigman said:
I am thankful for the advise I recieve here, and in turn I try ( whenever possible ) to return in fashion.

That's what it's about! Thanks Mike. :w


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