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While driving last nite with the cruise control for 10 minutes and coming to an off ramp I used the clutch to disengage the cruise control and to slow the car down (at first I tapped the clutch peddle to disengage the cruise control and that worked but as soon as the clutch was reengaged the cruise came back on). Everything was fine until I was on the off ramp with the clutch in and coasting then the engine all of sudden reved to red line and returned to idle. what happened? Could this be related to my dead clock issue? See "clock" posting.
It is hard to determine if they are indeed related or not. As you know there is a micro switch on the clutch pedal assembly, which is part of the cruise control deactivation device. This could be a fluke because the micro switch could have been temporary jammed for any numbers of reasons.
My suggestion is to track down and fix one problem at a time.
So that's concentrate on getting your clock issue fixed first and then we can help you on the cruise control issue, if it is a reproducible problem.
I don't think it's related to your clock. When you push your clutch in with the cruise control engaged, it will temporarily disengage the cruise control. Releasing the clutch re-engages the c.c.; if you are in neutral the engine will race. Your posting said the clutch was in and the engine raced, but perhaps you inadvertantly released the clutch with the transmission in neutral. If not this, then it would be a malfunction, probably in the switch that disengages the c.c. when you push the clutch in.
Tapping the clutch won't disengage the c.c., tapping the brakes will.
I am not sure you have a problem because my car does exactly the same thing! On the other hand, perhaps we both have the same problem.
When using cruise, if I clutch in, the cruise is interrupted until I get off the clutch pedal. If I put the press on the clutch and shift into neutral, the car will rev trying to get back to the set speed. In my car only the brake or the cruise lever will cancel the setting.
I did this only ONCE! I had the cruise control on and depressed the clutch. The engine immediately revved to redline and bounced off the rev limiter for a second or two until I tapped the brake pedal. I was caught completely off gaurd.
I assumed there was no connection between the clutch pedal and the cruise control.
My car has done the same for as long as I can remember--a real eye opener!
On my car:
-Cruise on, depress the clutch, cruise control disengages. No problem.
-Shift into neutral without disabling the cruise control (switch or brake), let up the clutch pedal, and the engine races.
As Dick has suggested, I'm sure the clutch pedal switch is only meant to momentarily disengage the c.c. while the pedal is depressed. Evidently, the system isn't smart enough to realize when the transmission is in neutral?? Anyone ever heard of a "transmission in neutral" switch?
I think the design thinking of this was this way you could push in the clutch and change gears and when you released the clutch, the same speed setting would be used. Might come in handy when towing my track trailer up a hill to shift from 5th to 4th?
Dick & Randall,
Now that you have posted how the clutch cruise control works, I may very well have done exactly just that. Will use the cancel lever or the brake to cancel the cruise control from now on. Nice misdesign by Porsche. what is the advantage of a momentary cancellation of cruise control via the clutch peddle?
Interesting idea those crafty Germans, I didn't know about the clutch / cruise design. Americans and Japanese manufacturers both designed their cars with clutch pedal that will disengage the cruise control completely.
As I thought about this a little more it makes complete sense to only disengage the cruise momentarily.
This is what I was thinking…
Say you are cruising at 75 mph and in sixth gear and the cruise control set at that speed. And all the sudden the roads starts to incline steeply, and then the engine had to work very hard to maintain the 75 mph speed since the car is in sixth gear. So at this time you can step in the clutch and downshift and release the clutch and the cruise control regain it’s preset speed.
Robin,
I like and am used to how the american and japanese companies set up their cruise control - both clutch and brake will cancel the action. Safety first.
Robin, I am sorry to disagree with you in that, in your scenario, I can just hit resume with the American and Japanese made cars. Rather than having the crap scared out of me when I see the engine race to the red line especially on a off ramp... glad I did not have the car in gear. Can you imagine how it will sound to the cop...uhhhh its not me, the car made me do it.
You don't have to be sorry, I wouldn't dare want everyone to agree with me on everything! I can't imagine what the world would be like..........
But what really sparks my interest is the German logic behind all of this. There are several other things in our p-car that really keeps me thinking too.
I.E.
(1).
The remote door lock signal light flash. It flashes twice for "lock" and once for "unlock", logically it would make more sense for an American the other way around, based on the the word "unlock" is two syllables (I think).
2nd thing is the tail mechanism logic, I still have not come up with any conculsion on that one yet.
What also interests me about the German logic is that they don't care what everyone else is doing, they just put their own design logic into production no matter what everyone else is doing. Well, at least that used to be their design logic....
Search led me here and was finally able to find my manual. Hope this helps someone in the future! Our 2011 BMW 328i cruise control operates the same way.....how thoughtful.
^ Yep, this is how it works. I use cruise a lot when driving on the highway.
On my 944S2, and maybe the 993 as well but I haven't had the same issue, the cruise control once stopped functioning and I couldn't figure out why. Then, one day soon after, I discovered my right rear brake light was out. I replaced the bulb and the cruise control worked again!
it turns out the cruise (on the 944 anyway) was wired into the brake light so it would cut off when you hit the brakes and activated the light. Conversely, this also caused the cruise to not function if there was burned out bulb and no complete circuit.
01-14-2002, 12:04 PM
engine rev. by itself
