Cruse Control Question

[89cab]

I have a 89 911 and I just noticed today that when i set the Cruz its works fine,But if I hit the brakes the cruz stays on. Not only that if I shift to neutral is stays on redlining my motor,I then had to press cancel on the cruse switch to get the motor to go to idle............So my guess is Porsche didn't think about those kind of scenarios when adding cruse control or something is wrong with my Baby???????

[switcher]

On my '87 911 the cruise control disengages when I hit the brakes; however, the manual indicates it you should not shift to neutral when it is engaged as it will, as you noticed, redline the engine.

edited to correct my faulty memory.

[89cab]

Originally Posted by switcher

On my '87 911 the cruise control disengages when I hit the brakes; however, the manual indicates it you should not depress the clutch when it is engaged as it will, as you noticed, redline the engine.

I will have to try hitting the brakes again thanks for the info.

[NewfieMZ3]

Your cruise should definately disengage with the brake, and I also thought with the clutch. I'd have it checked out.

[89cab]

Originally Posted by NewfieMZ3

Your cruise should definitely disengage with the brake, and I also thought with the clutch. I'd have it checked out.

What would it be if the brake does not disengage,Is it something simple.Probably not its a Porsche LOL

[Por_sha911]

I would be willing to bet that your brake lights are not coming on unless you press the pedal down pretty hard. The cruise disengagement is connected to the brake light switches. Ask me how I know... Check it out.
The clutch is not designed to disengage the cruise but it has a slight delay before the speed comes up. You need to tap the brakes before you step on the clutch (or disengage the cruise with the stalk).

[1986911]

Originally Posted by Por_sha911

I would be willing to bet that your brake lights are not coming on unless you press the pedal down pretty hard. The cruise disengagement is connected to the brake light switches. Ask me how I know... Check it out.
The clutch is not designed to disengage the cruise but it has a slight delay before the speed comes up. You need to tap the brakes before you step on the clutch (or disengage the cruise with the stalk).

I agree, check your fuse first if not trouble shoot the brake switch. I could be either A out of adjustment or B broken. Any completion of the brake switch circuit de activates your cruise control.

[porschenut]

Guys, disengaging the clutch is absolutely supposed to cut off the cruise control for as long as you have the pedal depressed. That is what the cruise control clutch switch in the tunnel is for. If your cruise doesn't cut off when you push the clutch pedal in, then your clutch switch is INOP. Here's the owner's manual for my 86 Carrera. Note what it says about disengaging when the clutch pedal is pressed:



Also search the forum for "cruise control clutch switch" and you'll find many discussions about it and the fact that failure of the switch is pretty common.

[Por_sha911]

P nut is correct. I'm thinking he's gotten shocked like I did when I stepped on the clutch and put it in neutral coming off the interstate and while I'm coasting down a long exit ramp and it starts revving when I didn't hit the brake. Scared the stuff out of me the first time it happened.

[Venetian]

Not to hijack but mine accelerates when I try to set the speed. It was working fine when I first got it. Never really worried about it because I seldom use it. Any ideas? Thx.

[wolf76]

i wonder if this my problem as well. I never mess with the cruise control but recently when I'm cruising around 4000 rpms or so and I step on the clutch to upshift the rpms jump to redline as though I'm still on the gas.


Chris

[Por_sha911]

Originally Posted by wolf76

I step on the clutch to upshift the rpms jump to redline as though I'm still on the gas. Chris

If it jumps as soon as you step on the clutch then your clutch switch is bad.
Venetian: It may be the stalk switch but the easiest (and cheapest) thing to do for starters is start by swapping out the brain with someone who has the same year car (87-88 and maybe 89) and see if the problem goes away. Its right under the radio. You can see it from the pass side floor. Two bolts and its out.

[nineball]

i gave up on the cruise in my 83. i have checked everything twice and had a p-mechanic go over it as well and found nothing wrong. when i turn mine on it does not hold the speed but it does sort of work. i can tell because the speed will decrease much, much slower than if i just lifted my foot off the gas pedal. let's say that if i take my foot off i can go from 70 to 50 in 3-5 seconds, when i turn on the cruise it will take a good 10-15 seconds to slow down the same amount.

[porschenut]

Nineball, that is the classic symptom of a cruise brain gone bad. You can get it rebuilt.

[nineball]

ya i suppose i could, but i almost never use the cruise in my other cars and they are no where near as fun to drive! i drove the car home from kansas to ohio and never even thought about using the cruise - i was too busy trying to soak myself into the seats to become one with the car

[89cab]

Originally Posted by porschenut

Guys, disengaging the clutch is absolutely supposed to cut off the cruise control for as long as you have the pedal depressed. That is what the cruise control clutch switch in the tunnel is for. If your cruise doesn't cut off when you push the clutch pedal in, then your clutch switch is INOP. Here's the owner's manual for my 86 Carrera. Note what it says about disengaging when the clutch pedal is pressed:



Also search the forum for "cruise control clutch switch" and you'll find many discussions about it and the fact that failure of the switch is pretty common.

So according to the top right corner of this manual it will Rev the motor if you are in neutral,so the only problem that I might be having is the braking issue I will check this out today.

[rgrimm]

The whole "reving in neutral" thing... It should remain disengaged as long as the clutch is in (look at the section on gearshifting in the manual photo...it is designed so if it's engaged, you can shift gears and when you let out the clutch, it automatically re-engages. If you leave the transmission in neutral and let out the clutch, it re-engages as it's supposed to and the engine takes off. Yeh, I discovered that the hard way...scared the s#%t out of me.

I always thought clutch switches were pretty robust. Brake switch adjustment can be off...I know I need to adjust mine this summer since I have to stomp on it pretty hard to disenage the cruise which means the brake lights aren't coming on unless the pressure is pretty hard either...and I'd just as soon not get rear-ended :-)

[89cab]

I just want to start by saying thanks for all your input today.So this is what I found out about my brake lights.When I press my the brake pedal the lights do not turn on right away, its takes some pressing with the size 10,about 1/2 way or so......So does that mean that I need to adjust my brake switch?

[89cab]

Originally Posted by rgrimm

The whole "reving in neutral" thing... It should remain disengaged as long as the clutch is in (look at the section on gearshifting in the manual photo...it is designed so if it's engaged, you can shift gears and when you let out the clutch, it automatically re-engages. If you leave the transmission in neutral and let out the clutch, it re-engages as it's supposed to and the engine takes off. Yeh, I discovered that the hard way...scared the s#%t out of me.

I always thought clutch switches were pretty robust. Brake switch adjustment can be off...I know I need to adjust mine this summer since I have to stomp on it pretty hard to disenage the cruise which means the brake lights aren't coming on unless the pressure is pretty hard either...and I'd just as soon not get rear-ended :-)

Ya it scared the s#%t out of me to.

[porschenut]

I'm not aware of master cylinder mounted brake switches being adjustable...