John52

The cruise control on my 92 coupe no longer works. Now cruise is something, I hardly ever use but the last time I tried it, nothing happened. There are no other apparent problems with the car. As part of the diagnosis process, it should be noted that I installed an RSA rear wing and 'jumpered' the connection to make the system think that the retractable wing is up (This procedure has been well documented in previous topics). I don't know if this could have anything to do with it since the cruise also checks for an 80 Kph speed.

Since I seldom use cruise, I am not about to take it to a dealer for diagnosis and repair, but if it was something simple to fix myself, I would.

Randall G.

Hi John,

The most common problem is the clutch pedal actuated switch--it's supposed to deactivate the cruise when the clutch pedal is depressed. If it's out of adjustment or the clutch pedal is not returning fully, your cruise will not activate.

You can see the switch at Robin Sun's website in the photos near the bottom of the page--it's the plastic box with wires coming out of it.

Cruise Control Switch

Good luck!

Herbie

Hallo, I've a similar problem, cruise control, on my '91 c2 cabrio tiptronic, works one time every ten;

But I've a tip, without clutch, and without clutch sensor.

What can I check, please ?

Thank you

Jack667

FYI -
I had a serious problem due to Cruise Control. I wonder if Adrian or anyone else has heard of a similar issue -
I just had my broken flywheel updated and of course had a new clutch installed as well. Driving home from the shop, the throttle pegged, for no apparent reason! I had some minor pedal response concerns and I had my mechanic on the cell phone when it happened. I was on the expressway, and paniced - cell phone in the ear didn't help... Rather than shutting the engine off, I goofed around a bit with the clutch etc, then I exited to a safe area and finally hit the switch while on the off-ramp, and came to a safe stop, thankfully.
With my mechanic still on the phone, I checked under the engine cover and found that the cruise control linkage (see picture) had lodged out of position, pinning the throttle in the full position.
On the ride home, it became apparent that the brand new clutch was fried - and it was replaced by the distributor under warranty, thanks to some schmoozing by my mechanic.
I have heard of this happening atleast once - to someone else. It was referenced in our local PCA newsletter, in a guest article from another region, in a piece about PPI's.
Needless to say, the part is no longer installed on my car, and I don't enjoy the cruise control feature...
Jack
1990 C4 Cab

Randall G.

Hi Herbie,

My cruise control came up lame a about a year ago, but it wasn't the typical problem with the clutch pedal switch. A tie-wrap had failed under the passenger seat, which in turn allowed a wire (for the cruise control) to slip into the seat track, where it was subsequently run over.

Of course, you can also check the fuse (#19, I believe), which the cruise control shares with the stop (brake) lights.

Good luck!

Jeff Curtis

There's also a switch for the brake pedal, I had problems with that when I first purchased my '91...check it out, you'll have to pull up the carpet and the board around the pedal cluster...have a shop vac handy, there's going to be a lot of junk down there!

Adrian

The most common cruise control problem is the microswitch under the brake pedal. The microswitch under the clutch does not disconnect the cruise control like the brake pedal microswitch does. It only interrupts the signal whilst the clutch is down.
A quick squirt of contact cleaner into the brake microswitch is often sufficient. Lack of use does not help.
There are many other possibilities as well but start with the brake switch, then the clutch switch just to be sure, then the switch on the column and after this, things get a little complicated. A TIP has a few additional features which may need to be considered.
The cruise control arm failure is well known and was the subject in a RECALL on the 964s fitted with cruise control.
Oct 92 Recall N04- Replacement of Cruise Control Rod. This was fixed by TSB 29204.
Ciao,
Adrian
911C4

Herbie

Adrian

- The brake switch is the same of stopligths ? Because they works fine;

- Pheraps, I found the wrong thing. Noticed that, to start cruise control, I have to move the arm up (there isn't a contact there, it's only a mechanical stop) and move it front and back a few times. And the cruise starts. Wrong/dirty contacts ?

Thank you

Adrian

Dear Herbie,
Very rare to find a European 964 with cruise control. I was actually answering the first poster.
From your description I think your cruise control selector switch has a problem. You will have to disassemble it and try and repair the contacts. They will be damaged I feel.
Ciao,
Adrian
911C4

Herbie

Dear Adrian

I described my problem with cruise control.

Now I can be more detailed.

To activate the cruise, I have to move sometimes the arm up, front and rear.

When it starts, the "frontal" position works fine (accelerate, and fix speed) and the "low" position too (recall a stored speed). The "back" position instead never worked. This position is to exclude cruise control or to lower the speed.

Can this be related to a pedal brake switch ? (that I didn't found!)

Then, I tried to disassemble the C.C. arm; this arm is hold in a "shell", made of two halves, an upper and a lower.

I removed the upper, undoing some screws and turning the wheel.

But I was unable to remove the lower half; it is forced by the wheel and the lower part of the dash. So I couldn't remove the arm. Should I remove the wheel ?

Are there any tricks to remove that lower shell ? Or, where can I find the terminals of the cruise control arm, to check them with an ohmmeter ?

My intent, for now, is only to determine if the defective part is the control arm or the control unit (that I'm still searching...).

Thank you

Adrian

Dear Herbie,
I have no experience with the cruise control control arm removal. I do not have this feature and nor do I want it. I have checked my data and you will have to remove the steering wheel to successfully remove the control arm and its wiring etc.
Failure of the control/switching arm is quite common and a pain in the butt to repair. Good luck and maybe you can share with the group your procedure for removal, repair and reinstallation,
Ciao,
Adrian
911C4

Herbie

Dear Adrian

Something about wheel removal ? I saw a couple of "torx" screws on the back of the weel; only these ? And air_bag wiring ? There is a risk of an explosion ?

The presence of cruise control option:
I consider it a not so useful optional, especially in italian higways (have you ever been there ?), but I want all things installed in my car must work perfectly.

I hate non_operating systems, circuits leaved open, unconnected mechanical set, et similia.

I can also decide to never use the cruise control, but, if it is present, it must to work. (am I a "taleban" ? )

Today I'm going to check the brake pedal switch, as you suggested in previous threads.

Thanks

Adrian

Dear Herbie,
When working on the steering wheel you must have the battery disconnected. You risk firing the airbag if you have an power in the system. All that holds the steering wheel on are the two screws you mention which is the airbag mounting and the steering wheel nut. If in doubt have it done by the professional. To remove the airbag pill you have to disconnect an electrical connector.
The airbag also has to be stored in a safe place away from children.
I have driven on Italian autobahns many times. We pop down to Milano for an ice cream in summer. Venice for a weekend trip.
Cruise control is useless on most European autobahns with the exception being eastern France.
Ciao,
Adrian
911C4

Herbie

OK, I'm not lucky.

Checked the brake switch (the only one I can see near the pedal; is it in common with brakelights?) and it works fine. However I sprayed it with a contact cleaner.

Waiting for the wheel removal (have to buy a torx screwdriver, first: $$$), I'm thinking:

There is a depression problem in my car, the tube from rear to the light orientation switch (a vertical wheel with "-2, -1, 0, +1") is blocked, no air passes through. The rimanent part of the circuit (to the headlight) is working.

I'm guessing: is that depression duct needed also for other services, like cruise control and climate control ?

This is another front to investigate.

Thank you

Herbie

Dear Adrian

OK, I removed wheel, airbag, etc. and checked my CC arm contacts... They are all OK, I guess.

The wires on the two halves of the connector are:

number arm side cpu side

1 blue blue
2 black orange
3 yellow yellow
4 brown green

(the number is printed on the connector)

The arm is a three_way switch; with those functions:

"Wie" (speed recall): shorts 1 and 4 (normally open)
"ein" (insert CC) : shorts 3 and 4 (normally open)
"aus" (stop CC) : opens 2 and 4 (normally closed)

Is that behavior right ? The "aus" behavior seems strange; normally closed ?

Thank you