Cruise control not working, where to start???

[Hendog]

Originally Posted by CJP5

The cruise does not engage at all. I've replaced the relay, checked the fuse...it's good, replaced the module.

Yesterday I received the Bentley manual and I went and bought a multi-meter. Couple of questions...

1. Bentley manual pg 960-12 lists the CC trouble shooting table and steps. Do you know if terminal 1 in the control module harness connector is the ground? Trying to make sure I'm testing correctly.

2. Are the Clutch pedal switch and the Brake light switch the same switch, are they two sep switches and are the both located in the "tunnel" under the center console? I had the pedals exposed and I do not see either of these switches. Based on my testing, if I'm doing it correctly, both these switches are faulty.

Thanks,

Chris

1. No, terminal 1 is HOT in run or acc. See Bentley page 970-62. Terminal 12 and 8 are ground. Anywhere on the chassis of the vehicle is also ground.

2. The Clutch switch and Brake light switches are not the same. There is one clutch switch, however I'm not familiar with its' location. There are two brake light switches, one for each side L & R, located on the brake master cylinder.

[CJP5]

Henri- Thanks for the ref to the wiring diagram page. I see the ground now. Time to re-test. Quick question, the manual doesn't state that the car should be running or in Acc when running the tests, except for one of voltage tests to check the brake light switch. Do you know if the tests are performed with the car off, acc, running for the Ohm tests?

[Lorenfb]

For more info read 'Generic' here: Problems
and read 'Cruise Control Systems' here: TECHNICAL

[CJP5]

We've got cruise!!!! I won't use it much, but I don't like anything on my car not working. It ended up being the clutch pedal switch. I recently had a shop replace the shaft/rod the pedals are mounted on. On the far right end basically under the tunnel is the switch. It has a tab on it that is actuated off the shaft by a tab that presses in or releases the clutch switch tab as you depress or release the clutch. The tab on the switch was bent down at a almost 90 degree angle. This kept the circuit open and wouldn't allow the system to engage. I bent the tab back straight and aligned it correctly. Being optimistic, I went for a drive and presto... It works! Replacing this would have been a b%#*$!

[jdbunda]

Originally Posted by Hendog

Reflow all the suspicious solder connections on the PC board of your cruise control module. That's what I did and it worked thereafter. Now, I'm an electronics tech and work with a soldering iron, so my apologies for sounding so flippant about the ease of effort.

The module is found underneath the dash. It's a silver box like this:

Remove the module, pull the plastic cover off, pull out the PC board and resolder a bunch of connections, mostly around the IC's and devices with heat sinks.

Hendog - thanks so much for posting this picture - Bentley shows this module in the luggage compartment behind a cover. I opened up my '86, pulled the cover and - no module - saved by this board again!

Thanks!!

[Chuck.H]

'Easiest' test is to try to engage the cruise while lifting up on the backside of the clutch pedal -- if the adjustment is marginal then this may engage the switch. I estimate I've used my cruise for 200k of my 300k miles, and this switch needs adjustment every 75k miles or so... it's the ONLY thing that has ever broken on my CC in all these years/miles.

Hope this helps,
Chuck.H
'89 TurboLookTarga 336k miles

[carreradpt]

Chuck, any pictures of this switch and the tab in question?

[JAR0023]

Originally Posted by carreradpt

Chuck, any pictures of this switch and the tab in question?

I'm also trying to troubleshoot my non-op cruise control. I was just checking the switch yesterday but did not take photos. Once I adjusted my switch I now get a click from the CC unit but still no CC.

Pull out all the carpet from drivers side including as much as you can from tunnel. Unsnap the accelerator pedal and fold it back. I used this to hold the tunnel carpet out of the way. You will see the front left front of the tunnel cut away near the pedals. You'll also see a hole in top of the tunnel ahead of the console.

Put your carpet beside the open door to save your knees. Stick your head all the way in up near the pedals and shine a light into the cutaway area of the tunnel. You should see the switch. Black switch with silver arm sticking out towards pedals. On my car the switch was making contact with the pedal but switch had slid back to that it was not actually triggered. If you are flexible and strong enough you can push the clutch with your hand and watch the contact between the two.

If you reach down into the hole in top of the tunnel you can feel two 10mm bolts/nuts. These are holding the bracket for the switch. I simply loosened these and slid the bracket/switch forward until it fully contacted arm of pedal cluster.

J

[Chuck.H]

Sorry no pics, but JAR023's description is pretty good. I'm curious about the click as mine engages and disengages with no sounds at all. Granted I always have my targa top off, but I really use it a lot, every day actually since I live on a 40mph speed trap road and I need to keep 'er down.

Make sure your clutch switch hasn't failed, and as somebody else said you need to also make sure your brake lights are not stuck on...

Chuck.H
'89 TurboLookTarga, 336k miles

[JAR0023]

I was suprised a little by the click myself. First 911 so I don't have any reference. Hard to hear with the car at speed but once I adjusted the clutch switch with the car on but not running there is a definate click from the CC module. If it's off I get a click when I pull the lever up. Then another click when I pull to turn cruise off. I need to double check the CC relay and location for my car but I could swear the click is coming from low on the dash. Click is definately new as I tried the lever prior to adjusting the clutch switch.

J

[Chuck.H]

I turned off the stereo this morning and even at 40mph listening hard I could not hear the click on or off - my '89 is dead silent...

Hope this helps,
Chuck.H
'89 TurboLookTarga, 336k miles

[urquattro83]

Can someone please confirm operating procedure for use of the cruise control lever on an '05 911?

Need to know if there's a separate switch to turn on the system, and which direction on the lever performs which function.

Thanks for your help!

[SpyderMike]

Here is the clutch switch assy removed from my 1985.

[SpyderMike]

In this picture you can see the silver switch actuator lever.

[pavegeno]

Just went through getting my CC fixed after intermittent operation. Mech#1 said it was the two brake pressure switches in the trunk. One was shot and the other was going bad. This is the same switch that senses brake pressure rise and turns off the CC and turns on the brake lights. Worked ok for a few days then more intermittent operation. Mech #2 (just moved to Germany) said it was the clutch switch. Picked up the car and it didn't work at all. Mech #2 went back in and said it was the control stalk on the steering wheel and replaced it. Has worked perfectly for the last 6 weeks.

Point is that I assumed this was a very simple system, but took some time to get right. Only thing I don't like about our CC is that there isn't a decelerate option. You have to cancel it, slow down, and then re-engage. Other than that, it works very nicely and I like the always on nature of it.

[Hokie6]

Hey guys - relatively new owner of an '81 Targa and first posting -

I've been troubleshooting my CC and so far haven't found any problems with the system. However, I do wonder about the CC switch itself and had a question about the operation of it. It seems to be a momentary contact for the on function (pull toward you). Should this be momentary or engaged (stay forward)? The up/down are momentary also. I'm thinking that if it doesn't lock in the forward position, then it's always off which would explain why it doesn't work -

Thx for the help -