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Discussion Starter #1
I'm a recent member and have been spending a lot of time reading many of the posts. :thumbsup: And have learned a great deal about my C4 in the process. :D

The problem I am having is with the cruise control. It has never worked since I purchased the car. I checked for vacuum leaks, checked vacuum break switch, replaced break lamp switch, and checked the resistance values on the servo. I thought I found the problem when I disconnected the connector from the steering column control unit. It is a two prong connector that has a conductive film on each side (effectively 4 connections). One of the sides pealed back and therefore no connection on that side. After jumpping the connector I am now getting power to the servo. After a test drive still no cruise control! :huh:

Can anyone tell me where the Cruise Control Module is located?
 

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Can anyone tell me where the Cruise Control Module is located....

Really there is not one.....
1. it starts with the multi-function switch on the steering column
2. through the brake switch, clutch switch for the manual trans.
3. taking a reading from the speed sensor and processing thru the dash cluster
4. using the vacume system..
a. vacume tank
b. check valve
c. vacume valve
d. vent valve
e. vacume motor
f. vacume release valve

but check the servo resistance to see if its in working order
measure between E & C 30 - 50 ohms
A & C 30 - 50 ohms
B & D 15 - 30 ohms
if not in range then replace the servo


this is a start.... can also be inserment cluster problems
 

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DC PIT CREW BOSS
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3... processing thru the dash cluster
Isn't this the module? I'm not sure about the '92 but on the later C4's ('95-'96) there was a cruise control module that was mounted on the dash support bracket at the right side of the steering column. The module interpreted the position of the servo, the position of the control switches and the output of the speed sensor. In response to these various inputs, the module electrically signaled the opening or closing of the vent and vacuum solenoid valves in the servo.


That's a good description of the system craig. Good idea and info on checking the servo too
 

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Discussion Starter #4
Isn't this the module? I'm not sure about the '92 but on the later C4's ('95-'96) there was a cruise control module that was mounted on the dash support bracket at the right side of the steering column. The module interpreted the position of the servo, the position of the control switches and the output of the speed sensor. In response to these various inputs, the module electrically signaled the opening or closing of the vent and vacuum solenoid valves in the servo.


That's a good description of the system craig. Good idea and info on checking the servo too
This was the procedure I used http://www.corvettefever.com/howto/82001/
I believe the module was a separate unit starting in 1990. So I'm thinking my '92 should have one somewhere. I checked under the dash and was unable to locate it there. I have an idea what it looks like because NAPA does list one for a 1992 http://www.napaonline.com/masterpages/NOLMaster.aspx?PageId=430&Keyword=cruise&KeywordCat=Cruise+Control+Module&VehCode=Y

I just got the car out of winter storage so I will recheck some of the items Craig suggested too. :thumbsup:
 

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Cruise control not working

I'm a recent member and have been spending a lot of time reading many of the posts. :thumbsup: And have learned a great deal about my C4 in the process. :D

The problem I am having is with the cruise control. It has never worked since I purchased the car. I checked for vacuum leaks, checked vacuum break switch, replaced break lamp switch, and checked the resistance values on the servo. I thought I found the problem when I disconnected the connector from the steering column control unit. It is a two prong connector that has a conductive film on each side (effectively 4 connections). One of the sides pealed back and therefore no connection on that side. After jumpping the connector I am now getting power to the servo. After a test drive still no cruise control! :huh:

Can anyone tell me where the Cruise Control Module is located?
I found there was a vac valve next to distributor cap on the drivers side close to the firewall that pulls vac off the plenum it had deteriated and my cruise was not getting vac to work. $4.00 dollar part at Dealership fix it.
 

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El Teafive
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90-newer the Cruise control Module is above the radio receiver (90-93) on the passenger side of the car. near the Aux fuse panel.

94-96 is in the same area but the radio receiver was moved to a different location.

84-89 the cruise control module was intergrated with the Digital dash
 

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Discussion Starter #7
After buying a Service Manual on ebay a few weeks ago, I decided to tackle my non-working cruise control today. The SM gives an excellent diagnostic chart. The only problem is accessing the Cruise Control Module and its connector located under the passenger side dash. It took me most of the day to finally access the CCM. It entailed removal of the glove box, passenger side lower panel & support, the upper trim pad, etc. Removal of the right side outer bracket finally enabled me to access the CCM.:thud:

I have not finished my testing but it seems that the set/coast button may be my problem. I am getting a voltage even when it is not being depressed. I believe this would result in a constant “coast” mode. Does this make sense?:huh:

I do have another question – Is there an easy way to remove the turn signal lever? :huh:

Thanks
 

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Cruise control not working

I'm a recent member and have been spending a lot of time reading many of the posts. :thumbsup: And have learned a great deal about my C4 in the process. :D

The problem I am having is with the cruise control. It has never worked since I purchased the car. I checked for vacuum leaks, checked vacuum break switch, replaced break lamp switch, and checked the resistance values on the servo. I thought I found the problem when I disconnected the connector from the steering column control unit. It is a two prong connector that has a conductive film on each side (effectively 4 connections). One of the sides pealed back and therefore no connection on that side. After jumpping the connector I am now getting power to the servo. After a test drive still no cruise control! :huh:

Can anyone tell me where the Cruise Control Module is located?
First of all find out if you have enough vac getting to the cruise control Diaphram, with the engine running pull the hose going to the diaphram, hook up a vac gauge to see if vac is present, if not backtrack to the supply line and find where it has stopped , mine was leaking Vac next to distributor it was a vac distribution Valve 7.00 dollars at the dealership, there was a crack in it.
If Vac is present on the supply line going to cruise diaphram, now pull a vac with a hand vac pump and pull a vacuum on the diaphram and see if holds any volume of vac is fine and see if it holds that vac. If the diaphram will not pull a vac and hold it then the diaphram has a hole in it.:thumbsup:
 

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Discussion Starter #9
yes the vacuum lines, servo, and both breaks switches check out as OK.

Per the SM check I should get a voltage when the set/coast button is pressed, if so it passes the test. But I am getting a voltage without pressing the button, whichs leads me to believe the "set" switch is stuck in the set mode. (SM doen't mention what to do if a voltage is present without pressing the button). I believe this would then cause a perminent coast situation and not allow the cruise to set.

I read that the turn signal stalk can be "yanked" out (not sure which year C4) but before I try that I'd like to know for sure?
 
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