ramius665

I've searched all over the forum, the FSM and google without luck.

I have a 1986 951 that came from the factory without cruise control. I acquired a known working cruise control brain and actuator. I bought a brand new column stalk. After installing everything, my cruise control still does not work. I retested each component on a car with known-working cruise control and verified that each component is functioning. After consulting the FSM, I confirmed that fuse 19 is not blown. Further, I checked the voltage on plug 1, pins 1 and 8 for voltage (according to the FSM, pin 1 is 12+ and pin 8 is ground). I get 6.85V at idle.

I understand that swapping LED brake lights can affect the voltage to the cruise brain, I have OEM light bulbs (all functioning). I have exhausted every test I can think of or research to fix this.

Please help me fix my cruise control before I drive 5000 miles round trip to Parade!

DewaneP

Not sure but wouldn't you have to add the switches at the clutch and brake petal?

pontifex4

Aaron, this is likely not your problem, but I found that on the way down to the Fest, I had to pry up on the clutch pedal a little to get the cruise to come on. On the way back, it wouldn't come on at all unless I held the clutch up. (Now that I've sneaked into your thread, maybe someone will tell me how to adjust the switch!)

ramius665

Well, I know of at least two cars with working cruise that don't even have the clutch switch connected. I neglected to say previously that I also installed the clutch kill switch as well (Charlie, it's adjusted by a lock nut on the threaded collar. Takes a 15mm wrench).

Does anyone have a link to the portion of the FSM that covers cruise control? Or even just the section?

I've also read that the cruise computer receives the speed signal from the trans, not the speedo as well.

I'm more than a little frustrated and confused here, I honestly thought this would be an easy addition.

John_AZ

Volume 1 (engine) chaper 27

http://www.texasblake.com/porsche/docs.html

John

ramius665

John, that was exactly the test plan that I was looking for after seeing it referenced in other places. With any luck I should be able to diagnose where the fault is.

CurtP

When you checked voltage on pin 1, were you using pin 8 as ground? If so, was there a voltage difference on pin 1 when you grounded somewhere else (like the body of the car)? If not, what do you get when you use pin 8 as ground?