944 cruise control servo pinout question

Charles · 10-20-2002, 03:09 PM

A couple of months ago, I pulled the cruise control servo from my 944 to check it at work (odd clicking noises at idle, and the system wouldn't engage on the highway even after mucking with the brake light bulbs).

Things seemed OK-- I could apply 12V to the clutch, and by feeding the motor terminals from a bench supply, I could get the actuator arm to move (and the potentiometer would respond accordingly).

The one thing that confused me was the "brake lights" wire on going to the servo. AFAICT, only the cruise control amplifier needs the brake light signal (for cancelling cruise control when you hit the brakes). Since the wire is "active high", it can't be used to directly turn off the clutch coil (which would allow the arm to return to the neutral position). Any ideas what that wire is needed for? It's pin 6 on the round connector, connected to pin 8 on the amp.

Interestingly, the 85/2 models (with the split servo/switch connector) don't seem to use this wire for the servo, and the motor, clutch and pot all have separate wires (no common ground).

I've given up on the amplifier... when I opened it up, I was assaulted by the smell of burned electronics. As someone put it, "it's much easier to get the magic smoke out of electronic components than to put it back in."

coupe · 10-23-2002, 05:08 AM

Hi there..Would you be so kind to tell me where I can find the Cruise control servo and the servo control unit???

Thanking you in advance
Coupe

Charles · 10-23-2002, 06:21 AM

To find the servo, look under the hood. As you face the front of the car, it's on the left behind the shock tower.

It's part #5 in the diagram below.

On '83-'85 cars, the amplifier is behind the kick panel near the accelerator (behind the center console). See part #1 in the diagram.

coupe · 10-23-2002, 11:32 AM

Ok Charles, thanks for all the great info. My car is a 944 Turbo, 1986. I now at least have a drawing to go by... Thanks friend.

coupe

Charles · 10-23-2002, 05:02 PM

I guess the board doesn't show image URLs by default, but that image came from elsewhere on www.pelicanparts.com. They have a bunch of pages scanned from the factory service manuals-- just poke around under the 944 tech info section.

coupe · 10-23-2002, 09:05 PM

Hi charles, I trully believe that my cruise control motor assy is missing. There is nothing between the battery and the shock housing... It may have been taken out a long time ago by the previous owner(s)...Oh well..

coupe

Charles · 10-23-2002, 09:11 PM

Stupid question, maybe... but is the rest of the stuff there? e.g. the amplifier and the switches on the turn signal lever. Cruise control was an option, I believe... if you have the switches, that doesn't eliminate the possibility that someone replaced the turn signal lever with the cruise-enabled one.

coupe · 10-23-2002, 11:51 PM

The cruise control switches are present, and a marking of where a clutch switched used to live. I have now compared it to another 951. All the gear has been pulled out on mine, including the
The control box.

So its not really such a 'stupid question'... Just give people a chance to learn about their cars will you??!! Thank you!!

Coupe

Charles · 10-24-2002, 05:07 AM

geez, don't get your panties in a bunch :-) I was only trying to help.

I meant that maybe my question (about whether the rest of the gear is there) was stupid... *sigh*

My original thread-starting question still stands-- has anyone out there played with the servo motor on a bench? I'm sure I can probe around and figure this one out, but not without the possibility of miswiring it and shorting the part out (and it's not a cheap part, either).

Lawrence Coppari · 10-24-2002, 05:44 AM

I've fiddled with mine several times trying to determine why mine does not work unless I uplug it, then replug it at the servo motor with the engine running. But sometimes it works without doing that. It has always worked when I unplug/plug it. Thing has a mind of its own!

I know my electromagnet is ok and the motor is ok. I've resoldered all connections on the brain board. I cleaned the sweeper contacts. When it entirely quits, I'll buy an aftermarket cruise. I've grown extremely tired of messing with it. Perhaps mine needs an exorcism.