Cruise control question

[kevstens]

I was looking at my cruise control in the engine compartment as it has a problem. When I set the speed It maintains it for about three minutes and then starts to slowly slow down. I thought I might have a vacuum leak so I was looking at the vacuum hoses. The larger hose that goes from the module then goes along the shelf at the firewall(between the shock towers) goes into a hole in the shelf. What does it attach to in that hole? I went to a local shop and they checked two cars that were there, a 1983 and a 1986, on both the hose pulled out of the hole and was not attached to anything. Is this correct? Kevin

[JerP]

Yes that is correct.

[Jesse16]

Same on my 87 with regard to the large hose (no idea why). It had a similar problem and my shop sent the module to someone who checked it and re-soldered some connections. Snapped it back in and it now works fine.

[Lorenfb]

"It had a similar problem and my shop sent the module to someone who checked it"

Jesse it correct in that the most likely problem is a bad cruise control module.
The vacuum actuator and its hookups are rarely if ever the problem.

For more info, read here under "Cruise Control Systems":

TECHNICAL

And if the module is bad, call Pelican Parts even if the module is not shown in the catalog,
as they have many sources for Porsche parts.

[DRACO A5OG]

There are actually two hoses, one larger and one smaller, smaller is the vacuum hose right behind the larger which is the breather on the Servo in the engine bay.

Make sure the small vacuum hose is connected.

In my case, my wrench forgot to connect it, I reconnected it, all good.

[kevstens]

What does the larger hose from the from the solenoid attach to after it goes down the hole in the shelf between the rear shock mounts? Kevin

[kodioneill]

Most likely the ECM Look on Ebay there is a re builder that does a lifetime warranty for $90 bucks fast turnaround. I have had many of these rebuilt buy this business and they are all working perfectly.


eBay My World - circuit_solutions

[Lorenfb]

"Most likely the ECM Look on Ebay there is a re builder that does a lifetime warranty"

Wasn't aware that Ebay or the rebuilder was a supplier/sponsor of Pelican Parts,
i.e. To help provide for funding the Pelican forum. Is this the case?

[db_cooper]

Originally Posted by kevstens

What does the larger hose from the from the solenoid attach to after it goes down the hole in the shelf between the rear shock mounts? Kevin

The servo (vacuum motor..solenoid) is vacuum operated..the small hose. When the unit disengages (brakes on or turning the cruise off), it needs a very fast supply of air to release the throttle..the big hose. The big hose must be open to atmosphere and is simply tucked out of the way.

[kevstens]

Thank you everybody! Kevin

[cpa]

The hose in the engine compartment that threads into to frame work is the vent hose. It goes into the frame to keep it from getting engine grease. Your problem is a common one caused by the resistance in the contacts in the ECM manufactured by VDO. It is very common. You can find a reputable repair facility on this forum but don't use Electronics Repair in Tenn. I sent one back to them three times under gaurantee with not good results. Each time it cost extra shipping. It took consiserable effort to get a refund after I told them to keep it and refund the repair cost. I had spent enough sending it back and forth. Good Luck cpa

[Nick Triesch]

Could someone please post a picture of the speed control module and where it is located on my 85 911 so I can send it out to be repaired? I have the same problem. Thank you, Nick

[kodioneill]

Open the hood and remove the black cover just under the windshield and you'll see it mounted in the driver side area. Rectangular silver box 3" x 5".

[whiz05403]

My cruise control surges when I set it, then goes idle thrust, then surges, then goes idle again. What's wrong with mine?

Thanks

[DRACO A5OG]

+1 Nick, in the truck behind that black cardboard cover to the right.

[Nick Triesch]

please help. when I pulled out the speed control module unit some of the little wires pulled out of the plug. They fall out easy! there are about 10 of them don't want to mess up and put them in wrong to ruin new unit! Could someone send a clear picture maybe? I have a 85 911. Thank you, Nick

[Nick Triesch]

Never mind. I put the wires in the correct way. I bought a used module on ebay and cleaned the pins and installed and IT WORKS!!!!!! Would not hold the set speed before and I took it for a test and it now holds!! So what I read it right, if the car will not hold speed, many times it is the module. Nick Next, the clock and then the only thing left after that is to fix the dome lights. They only work when you switch them on...not when you open the door.

[DRACO A5OG]

Originally Posted by Nick Triesch

Never mind. I put the wires in the correct way. I bought a used module on ebay and cleaned the pins and installed and IT WORKS!!!!!! Would not hold the set speed before and I took it for a test and it now holds!! So what I read it right, if the car will not hold speed, many times it is the module. Nick Next, the clock and then the only thing left after that is to fix the dome lights. They only work when you switch them on...not when you open the door.

PMed you