Cruise control not working after battery exchange

[royp4]

A week ago I replaced my weak battery. After the replacement, my cruise control dash light won't come on, and the cruise control won't function. Fuse appears to be good. Any ideas greatly appreciated.  Thank you.

[Loren]

There are still three light bulbs used in the MY2001 and newer LCD clusters.

 

[creekman]

Roy,

 

Do you have the Duarmetric program to erase faults...  That might be one shot, is Loren suggesting that if you had a bad lamp that would make the C/C in-op?  Have you depress the button on the end of the windshield stalk.  I think that's right?

[Richard Hamilton]

Yes, a bad c/c bulb in the instrument cluster will stop it working.

[DBJoe996]

Easy enough to check if it is the bulb.  Turn ignition key to the first position where all the lights come on and see if the cruise control light comes on.  Just tried this on my car and it came on for about 2 seconds, and then goes off.

[royp4]

Thank you all. I will try this tomorrow.

[royp4]

Just wondering, how difficult is it to replace the c/c bulb if it is blown?

[JFP in PA]

7 hours ago, royp4 said:

Just wondering, how difficult is it to replace the c/c bulb if it is blown?

 

See Loren's diagram above, you need to pull the cluster to get at them.

[royp4]

I tested the bulb per suggestion posted earlier. The bulb does light up when the ignition key is switched to the first position, so the bulb is not the problem. Any other suggestions greatly appreciated.

[JFP in PA]

I think it is time to get the car scanned with a Porsche specific diagnostic tool.

[DBJoe996]

I seem to remember this - check your brake lights, all of them including the middle light in the spoiler.  Manually cycle your spoiler up to engage the middle brake light and make sure they all work.  There are also two switches that disengage the cruise control (but do not turn it off which appears to be your problem).  One is the clutch pedal switch  and one is the brake pedal switch.  But I don't think your problem lies there.  You did check Fuse B-7...right?  Anything else strange happening electrically with the car?

 

There are two switches on the clutch pedal. There is another switch that senses the clutch is not depressed (it is located on top of the clutch pedal) This switch has to be made (clutch in up position) in order to turn the CC on. From my reading, the upper switch must be engaged for the CC to even turn on.  Check the plastic plunger on the upper switch.

Edited January 18, 2017 by DBJoe996

[royp4]

Thank you DBJoe. I will check this and report my findings. I really appreciate your taking the time to respond. I am familiar with the switch on top of the clutch pedal. Not sure where second switch for clutch is located though.

[royp4]

I have received new clutch switch and hope to install this weekend. I'll keep you posted. Thanks all!

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[royp4]

Ok, I have replaced the clutch switch. Still no joy. The green cruise light comes on when ignition switch is turned but goes out as soon as engine starts. Any further ideas greatly appreciated.

Thanks in advance

[Richard Hamilton]

What is the exact model and year of the car?  (Just to know if it is mechanical throttle or eGas). 

 

If it is eGas, I think you should get it hooked up to a Porsche tester.  It may possibly have lost its coding when the battery was changed.  Also, you will be able to test the stalk and switch input signals.  For example, the brake light switch has two sets of contacts (one normally open, and one normally closed) so although the brake lights might work, the cruise may not.

 

The mechanical throttle cruse control is completely different, and there are no diagnostics available with a Porsche tester.

[royp4]

Miraculously enough, cc is now working perfectly. We'll see.....

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[royp4]

Update on my previous update: After removing and reinserting key into ignition, the cc is working perfectly. I have no doubt that the clutch switch was defective, as the plunger was stuck and would not compress or release. Hoping for continued good luck. I was afraid I was going to have to replace the stalks. Thank everyone for taking the time to help me out. I really appreciated your suggestions. I will keep you posted of any further developments. Hopefully there won't be any!

[royp4]

Cc still working. Guess clutch switch was the culprit. Thanks all.

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