Cruise Control
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Joined: Dec 2008
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From: Belmar, NJ
Cruise Control
I just bought my car recently and had it in the shop to fix the cruise control. I'm being told by them that it can't be fixed easily due to the rear wing that was installed in place of the retractable stock unit. Supposedly there is a module missing for the cruise control unit that I'm guessing was on the old wing. The mgr didn't have all of the info and was going to get back to me after he talked to the mechanic on the subject.
So does anyone know how the system works? Is there something that is mounted on the retractable wing that once you replace it the cruise control doesn't work? I would think that if that was the case the module could be relocated somewhere else when the new wing was added. This was done by the previous owner and it appears to be a FVD wing, not some piece of garbage so I would think that FVD thought about this ahead of time.
Any help would be appreciated.
So does anyone know how the system works? Is there something that is mounted on the retractable wing that once you replace it the cruise control doesn't work? I would think that if that was the case the module could be relocated somewhere else when the new wing was added. This was done by the previous owner and it appears to be a FVD wing, not some piece of garbage so I would think that FVD thought about this ahead of time.
Any help would be appreciated.
Race Car
Joined: May 2005
Posts: 4,902
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From: The Bluegrass State
The cruise control module is tucked back on the engine toward the fire wall. It is very hard to access with the engine in the car. The retractable wing has nothing to do with the cruise control system. I had a fixed TT wing on the back of my car and the cruise worked fine. The shop manager is either mistaken or was told he wrong information.
Mike
Mike
Three Wheelin'
Joined: Oct 2006
Posts: 1,394
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From: Tampa, FL
Just a quick check since if I remember correctly you just got the car. Is yours an earlier car? There is a device behind your clutch pedal called a kinematic lever that was updated a number of times. Earlier versions would not allow the clutch to return fully although in many cases it feels/drives fine; however, the clutch pedal needs to return fully so it can engage a cruise control switch.
If you are not familiar with this, you can try driving the car at cruise speed, popping the clutch lever up with your toe, then putting on the cruise.
dave
If you are not familiar with this, you can try driving the car at cruise speed, popping the clutch lever up with your toe, then putting on the cruise.
dave
Three Wheelin'
Joined: Feb 2007
Posts: 1,508
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From: Westchester NY
I had an issue with the cruise. There is a small micro switch under the wood panel near the clutch pedal. The switch was bent and not in the correct position. When it was like that, it was like as if my foot was on the clutch and I could not set the cruise. Pull up the rug and the wood near the pedals and check that switch.
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Joined: Dec 2008
Posts: 93
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From: Belmar, NJ
Just a quick check since if I remember correctly you just got the car. Is yours an earlier car? There is a device behind your clutch pedal called a kinematic lever that was updated a number of times. Earlier versions would not allow the clutch to return fully although in many cases it feels/drives fine; however, the clutch pedal needs to return fully so it can engage a cruise control switch.
If you are not familiar with this, you can try driving the car at cruise speed, popping the clutch lever up with your toe, then putting on the cruise.
dave
If you are not familiar with this, you can try driving the car at cruise speed, popping the clutch lever up with your toe, then putting on the cruise.
dave
I had an issue with the cruise. There is a small micro switch under the wood panel near the clutch pedal. The switch was bent and not in the correct position. When it was like that, it was like as if my foot was on the clutch and I could not set the cruise. Pull up the rug and the wood near the pedals and check that switch.
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From: Boston, MA
As black ice mentioned, if your pedal does not return all the way you'll have a non-working cruise (ask me how I know). Pop it with your left toe and try to set the cruise.
As far as the wing... I do believe that a speed signal goes through the wing control unit. If the wing control unit has been taken out I believe that it's an entirely posible cause for a non-working cruise control. This one is from a hazy memory of someone posting something to that extent a few years ago, so you might want to do a search. I might be mistaken on this one.
As far as the wing... I do believe that a speed signal goes through the wing control unit. If the wing control unit has been taken out I believe that it's an entirely posible cause for a non-working cruise control. This one is from a hazy memory of someone posting something to that extent a few years ago, so you might want to do a search. I might be mistaken on this one.
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Drifting
Joined: May 2006
Posts: 3,074
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From: Paris
The cruise control malfunction could generate from several issues, but things to know,
in my understanding cruise control has nothing to do with the wing.
First, check fuse number 19, this is for the brake light and is one parameter for cruise control function.
Other monitors are clutch switch and speedometer signal.
The Cruise control does not function under 54 km/h, I do not know exact mph level for US. hope this helps.
in my understanding cruise control has nothing to do with the wing.
First, check fuse number 19, this is for the brake light and is one parameter for cruise control function.
Other monitors are clutch switch and speedometer signal.
The Cruise control does not function under 54 km/h, I do not know exact mph level for US. hope this helps.
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Joined: May 2001
Posts: 3,651
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From: Chino hills, CA
Like other have mentioned it could be an out of adjustment microswitch or the cruise control actuator module could be bad. I had to fix several units already by fixing cold solder joints inside the actuator's PCB. Interestingly the crack cold solder joint were all in the identical spot. Atleast the crappy German soldering is consistent. You may be able to pull the cruise control actuator without taking off the intake manifold on a 95, but I know for sure the intake manifold will need to come off on 96+ 993s.
Or you can get it done when you drop your engine in the future.
Or you can get it done when you drop your engine in the future.
Race Car
Joined: May 2003
Posts: 4,243
Likes: 103
From: SoCal
"I had to fix several units already by fixing cold solder joints inside the actuator's PCB. Interestingly the crack cold solder joint were all in the identical spot. Atleast the crappy German soldering is consistent. You may be able to pull the cruise control actuator without taking off the intake manifold on a 95, but I know for sure the intake manifold will need to come off on 96+ 993s."
Do what???????
There're actually five key elements to the Porsche cruise control system:
1. The cruise control actuator which is basically a clutched motor that
pulls on the accelerator linkage and is located in the engine compartment.
This unit has NO electronics other than; a motor, a solenoid, and a variable
resistor and NO PCB inside.
2. An ECU module which conatains all the electronics, e.g. a microprocessor,
which "drives" the actuator, senses speed, monitors the control lever,
& the pedal switches.
3. The control lever which is located on the steering column.
4. The brake switch which disengages the system when the brakes are applied.
5. The clutch switch (non-Tiptronic vehicles) used to disengage the system when
the clutch pedal is depressed.
The most common problems are (ranked):
1. the pedal switches
2. the power fuses
3. the ECU
4. the actuator
5. the control lever
Do what???????
There're actually five key elements to the Porsche cruise control system:
1. The cruise control actuator which is basically a clutched motor that
pulls on the accelerator linkage and is located in the engine compartment.
This unit has NO electronics other than; a motor, a solenoid, and a variable
resistor and NO PCB inside.
2. An ECU module which conatains all the electronics, e.g. a microprocessor,
which "drives" the actuator, senses speed, monitors the control lever,
& the pedal switches.
3. The control lever which is located on the steering column.
4. The brake switch which disengages the system when the brakes are applied.
5. The clutch switch (non-Tiptronic vehicles) used to disengage the system when
the clutch pedal is depressed.
The most common problems are (ranked):
1. the pedal switches
2. the power fuses
3. the ECU
4. the actuator
5. the control lever
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Joined: May 2001
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From: Chino hills, CA
[QUOTE=Lorenfb;6156506
1. The cruise control actuator which is basically a clutched motor that
pulls on the accelerator linkage and is located in the engine compartment.
This unit has NO electronics other than; a motor, a solenoid, and a variable
resistor and NO PCB inside.
[/QUOTE]
Loren, the variable resister is part of the PCB, the cold solder joint I observed are all solder joints on that PCB.
1. The cruise control actuator which is basically a clutched motor that
pulls on the accelerator linkage and is located in the engine compartment.
This unit has NO electronics other than; a motor, a solenoid, and a variable
resistor and NO PCB inside.
[/QUOTE]
Loren, the variable resister is part of the PCB, the cold solder joint I observed are all solder joints on that PCB.
Three Wheelin'
Joined: Oct 2006
Posts: 1,433
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From: On the Faultline
Not to confuse the issue but another potential source of your problem may be the control unit for the original, moveable wing (located in the passenger footwell). It's tied into the same speed sensor the CC uses and if it was tinkered with when they installed the fixed wing it could have disabled the CC. I'd check the other items first as they're more likely the problem but if you run out of ideas keep this possibility in mind.
Race Car
Joined: May 2005
Posts: 4,902
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From: The Bluegrass State
Not to confuse the issue but another potential source of your problem may be the control unit for the original, moveable wing (located in the passenger footwell). It's tied into the same speed sensor the CC uses and if it was tinkered with when they installed the fixed wing it could have disabled the CC. I'd check the other items first as they're more likely the problem but if you run out of ideas keep this possibility in mind.
When I installed my TT tail on my car I removed (as do many) the movable wing module in the passengr's footwell (I've done it on 2 cars now). It never caused an issue with the CC. Just adding some additional info here not saying I am an expert.
Mike
Race Car
Joined: May 2003
Posts: 4,243
Likes: 103
From: SoCal
"the variable resister is part of the PCB, the cold solder joint I observed are all solder joints on that PCB."
There's no PCB (Printed Circuit Board), as there're NO traces nor other components.
The unit inside is actually a thick film resistor as used in the 3.2/964 AFMs
with a wiper.
Furthermore, the actuator is the LEAST likely element to fail in the cruise
control system. This actuator is also used by Mercedes Benz which also
exhibits an extremely low failure rate.
Note: The speed signal (from the speedo pin "A") feeds a number of devices,
e.g. the spoiler ECU, the tach, & etc., none of which with its removal can cause the
failure of the cruise control.
Bottom Line: But then again, some enjoy doing a "shotgun" approach to troubleshooting.
There's no PCB (Printed Circuit Board), as there're NO traces nor other components.
The unit inside is actually a thick film resistor as used in the 3.2/964 AFMs
with a wiper.
Furthermore, the actuator is the LEAST likely element to fail in the cruise
control system. This actuator is also used by Mercedes Benz which also
exhibits an extremely low failure rate.
Note: The speed signal (from the speedo pin "A") feeds a number of devices,
e.g. the spoiler ECU, the tach, & etc., none of which with its removal can cause the
failure of the cruise control.
Bottom Line: But then again, some enjoy doing a "shotgun" approach to troubleshooting.