[bva]

Cruise Control will not engage. I don't use it frequently, but it was working a month ago. Any diagnostic suggestions?

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[flash]

check the fuse first

also check your brake lights - if there is a fault there, it won't let the cruise engage

blink test?

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[bva]

cruise control wasn't working on tech day and blink test had no faults. fuse is good, brake lights are good.

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[flash]

hmmm - sure wish i knew that then - i would have looked into it - i'll poke around and see what i can figure out from here

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[SILVY968]

When I got my 968 from the PO, the cruise was not working. The easiest thing to get at was the servo control under the hood by the battery; that was not the problem.
I would check the switch on the brake pedal; mine was ok.
The computer fixed my cruise control. I found one from a salvage yard on ebay. not hard to replace. No way to test for a bad computer, only process of elimination. It has the most components that can go wrong. Law of averages.
Brian

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[Anchorman]

The cruise control computers are pretty notorious for failing - the cause generally accepted is cold solder joints. I'm on my third computer in 6 years - and I use cruise control very often (every day) so having it functioning is very important to me. I was told that repairing the circuit board is easy - but after having opened one up, I decided it wasn't "easy" for me. I still have a spare computer for when the one currently in the car fails, but there's no certainty that it's good - can't know until it's installed. I've purchased all of my units on eBay.

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[gryphon]

<!--quoteo(post=69163:date=Mar 22 2009, 05:04 PM:name=Anchorman)-->QUOTE (Anchorman @ Mar 22 2009, 05:04 PM) <{POST_SNAPBACK}><!--quotec-->The cruise control computers are pretty notorious for failing - the cause generally accepted is cold solder joints. I'm on my third computer in 6 years - and I use cruise control very often (every day) so having it functioning is very important to me. I was told that repairing the circuit board is easy - but after having opened one up, I decided it wasn't "easy" for me. I still have a spare computer for when the one currently in the car fails, but there's no certainty that it's good - can't know until it's installed. I've purchased all of my units on eBay.<!--QuoteEnd--><!--QuoteEEnd-->

I bought my 968 with a non-operative cruise control--duhh should have had it inspected. It turned out to be the module. My electronic wizard buddy took it apart and checked it out, and as I recall it was three layer circuit board and not easily repaired. But I found one on ebay very cheap. If you have access to a second 968 as I did, a swapout to diagnose the problem is the easy way to go.

Tom

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[bva]

i pulled the module and removed the circuit card. a visual inspection didn't find any separations due to a cold solder joint. the conformal coat was intact, no burnt parts, and all the components had a good bond to the board. all low-tech through hole stuff with minimal flex in the card. found a module on ebay; guess i will have to buy it to be sure.

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[jeffski1]

This has been on my 'to do' list for a while. My cruise works, but it surges horribly. Anyone experienced that problem?

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[flash]

are you sure? have you tried it since we fixed the vacuum leak?

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[jeffski1]

Yep. Still surging. That's what I was hoping the problem was.

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[bva]

Jeff,
in researching my problem, i found the following, on clarks-garage.com

http://www.clarks-garage.com/pdf-manual/elect-04.pdf

your surge problem may be attributed to the servo unit.

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[rxter]

Funny. I used mine a bit up and down 5 last week. I did notice that it has a bit of a kick post-engagement. Maybe 3 mph - not hte 5 to 10 listed in the Clark's article. My solution? You guessed it - engage at about 3 below where I want to be. Worked like a charm...

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[gbarrier]

When we first bought ours, it would accelerate 3 mph when engaged and then work fine. I seldom used it. I loaned my car to my son who had to go on a long road trip for work and had just taken his car apart and was waiting on parts. He uses the cruise reloegiously (unlike Me). By the time he returned it was perfect and has been ever since then. Think the servo just needed to be exercised to loosen up the old grease. Also, remember that the brain is the same as late 944s so easy to find.

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[jeffski1]

Brother Gaucho,

Thank you for the nice find. With everything else that's going on with the car, this was way on the back burner. But since I am now waiting for a new water pump, I think this will be a nice to look into this a little bit.

Thanks,
Jeff

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[pipalli]

My clutch pedal has a pushbutton switch that closes when the pedal is pushed. I think it is there to deactivate
the cc while shifting. Something to check if you have a 6-speed.
JP

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[bva]

Problem Solved!

short story: clutch pedal switch is open when you press the pedal, closed when you release the pedal - my switch remained open constantly sending a disengage signal to the cruise contol box. pulled the switch, douched with contact cleaner, reinstalled and reset the jam nuts and viola.

long story: pulled the circuit card again yesterday, got it under the microsope and even though it looked good, I reworked the solder joints from the main connector to the board anyway. FWIW, single layer board, big spacing between pads, easy to rework if you've got a good iron and a semi-steady hand. reinstalled and still inoperable. pulled the servo unit last night, opened it up and cleaned the contacts IAW the clarks write up. reinstalled and still inoperable. even buzzed the switch on the brake pedal to verify but didn't think to check for a clutch switch.

good call JP. thanks

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[flash]

good iron and a semi-steady hand - sure wish i had that approaching the green sometimes

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