cruise control that sticks

[Dadoo]

I have a cruise control that works abnormally.
When I depress the control, the cruise sets and continuosly accelerates.
I noticed that it sometimes works fine on really hot days.
This is a 90' 944 S2 Cab.
Has anyone had a similar problem and a fix?

[Dadoo]

I use the cruise control frequently. I live in Chicago and I often take road trips to Toronto. It's something I got really used to using with my winter car.

[ribs]

Mine when engauged in cool to cold weather (65 deg F or colder) will continuously accelerate. One time I let it go up to 120 to see if the cruise has a speed cut off...I don't believe it does. In warm weather, it works beautifully though. I imagine there is something wrong with the control box (duh), but it doesn't worry me enough, all though on long trips the cruise is really nice. Get another control box for the cruise control, or if you figure out how to fix yours, let me know.

------------------
ribs, 86' 951

[RPM'S S2]

Weird. My 89 S2 has the same problem. Thinking back on it it does tend to work fine in hot weather and intermitently at other times. I'll worry about it in October!

------------------
89 944 S2

[TomH]

thought I read hear or over on Rennlist that the cruise control had a problem with sticking, might even be a service bulletin about it.

[turtle944]

Its actually a recalled item on earlier cars. I have an '84 and it was a recalled. The metal bushings would stick and cause the car to accelerate.
Here is the recall notice:

Component: EQUIPMENT:SPEED CONTROL:LINKAGES(12:83)
Manufacturer: PORSCHE CARS N.A. INC.
Year: 1984
Make: PORSCHE
Model: 944
Potential Number of Units Affected: 5916
Manufactured From: SEP 1984 To: JAN 1985
Year of Recall: '85
Type of Report: Vehicle
Summary:
METAL BUSHINGS FOR THE CRUISE CONTROL LINKAGE ARE SUBJECT TO CORROSION DUE TO WEATHER CONDITIONS. ALSO, THERE IS NOT ENOUGH CLEARANCE BETWEEN THE BUSHINGS AND THE SHAFT; AND THE LINKAGE POINTS WERE NOT LUBRICATED. THUS, CRUISE CONTROL LINKAGE CAN BIND, CAUSING THE ACCELERATOR PEDAL TO STICK IN A DEPRESSED POSITION. CONSEQUENCE OF DEFECT: THE VEHICLE, WITHOUT WARNING, WOULD CONTINUE AT SET SPEED AND CAN'T BE REDUCED. THIS COULD RESULT IN LOSS OF CONTROL AND AN ACCIDENT.


REPLACE THE METAL BUSHINGS WITH THE PLASTIC VERSION. VEHICLE DESCIPTION: PASSENGER CARS EQUIPPED WITH CRUISE CONTROL.

SYSTEM: CRUISE CONTROL LINKAGE.

[Kaos]

I won't take credit for this; I saw this on Rennlist two days ago.


Subject: Re: Cruise control
From: Atlanta951@aol.com
Date: Sun, 17 Jun 2001 18:28:24 EDT
X-Message-Number: 21

once again....this is THE fix. got it off the old 'porschelist' i've saved
it for years now and re-posted it several times.
good luck!

Brian Young
Atlanta
89 952
Huntley MAF Stage 3, ARC2/ARM1, HKS EVC IV, Autothority 2.7 chips, C2 17's,
V1...

Repost of my cruise control repair by multiple requests. :-) The cruise
control 'brain' chronically fails in many Porsches. No year seems to be
immune, but the earlier cars seem to be afflicted more. The same
controller is used in the 911 and 928 series, so this fix should work for
them, too. Compare part numbers to be sure.

Subject: Procedure: Cruise Control Fix.
From: Gregor Diseth
Date: Wed, 11 Nov 1998 21:44:02 -0800 (PST)

It has been noted on the FAQ and on the list that the 944 cruise control
is subject to chronic failure - failure to hold speed, acceleration above
a preset speed, and other ailments. As you may have guessed, I was a
victim of such a failure. My CC would always add 10 MPH to the speed that
I set. After 10 minutes or so, it would sometimes behave normally.

I have discovered a cure for the 'adding speed' symptom, and possibly
others as well. I just did this minor surgery on my '89.. and the CC is
flawless in its operation now.

You can disassemble, inspect and carefully clean the contacts inside the
servo unit mounted in the engine compartment. The assembly is fairly
straight forward, just take notes as you take it apart so you can
reassemble. Be careful with the carbon trace.. it is easy to literally
wipe it off. If it is worn, you can carfully bend the contact to run on
an unused portion of the trace. Makes sense when you see it. Use some
dielectric grease when reassembling.

Otherwise, this requires minor surgery on the CC 'brain' which is located
in a flat silver aluminum box above the hood release by your knees. If
you are comfortable with using a soldering iron and know the basic
concepts of soldering, you can fix this yourself. Following the usual
precautions, unplug and remove the box. If it won't come free, you have
forgotten a mounting nut, so don't force it. The upper right one is
somewhat hidden. Once out of the car, you want to remove the printed
circuit board from the box. Carefully bend the aluminum crimps with a
small screwdriver and gently slide the board free from its grooves.

Once removed, examine your printed circuit. You probably find it was
dipped in clear enamel or similar compound, as mine was - presumably to
protect from moisture/corrosion. Inspect the solder side of the board.
A magnifying lens of some sort is helpful, but not required. I discovered
my board had at least a half-dozen cold or otherwise bad solder joints.
These were mostly associated with small, square capacitors on the other
side. The bad solder joints I found had a concentric 'ring' around the
actual leg of the soldered component, as if the solder had either migrated
or actually cracked, breaking contact. The cure is to get your soldering
iron, and resolder the joints. A solder removal tool is helpful, as the
clear enamel coating interferes with resoldering the joint.. try to remove
it when it is heated. I have a 'solder sucker' and I just sucked out the
old solder and enamel as I heated the joint. Add some solder and be sure
it flows into the joint. Watch that you don't accidentally bridge two
pads with solder. If you do, heat and remove the excess and re-solder. Be
careful not to overheat and cook the joint or component on the other side.

I repaired about 10 suspect joints on my board, then put everything back
together. Needless to say, my cruise control has performed flawlessly for
the past 3 weeks or so (update - over a year now - still perfect)

I hope this works for you. If not, you probably have a defective
component in the CC controller. If you can identify and replace it, do
so. Otherwise a replacement CC controller is the only option.

Usual disclaimers - I can't be held responsible if you damage your car
while attempting this fix, or if your cruise control floors the
accelerator pedal and makes you go 137 MPH. The procedure is relatively
easy and risk free, if you are careful.

Feel free to e-mail with questions or comments. I would like to hear from
folks doing this procedure.

-Gregor '89 944 2.7. Join the 924/944/968 webring at
http://www.efn.org/~gsdiseth/944.html

[pearldrum]

well, if u get pulled over for speeding, blame it on the cruise control, and did not realize u were accelerating.