I have a 2004 C4S Cab and suddenly my speed control doesn't work. When I push the button on the stalk, it lights up on the dash, but won't set. Any recommendations are welcome?

 

I would start by checking the brake light bulbs, many German cars rely on properly functioning brake light bulbs for operation, as odd as that may sound. Also on occasion the clutch switch(es) and brake light switch can cause the cruise to not work...

 

Thank you, I'll check it out.

 

Checked out the brakes lights and they are working properly. Please advise how to check out the clutch and brake light switches. Other suggestions also welcome.
Thanks!!!

 

I checked mine on my BMW with a multimeter. They were inexpensive so I just replaced both switches and my cruise now works in that car.

 

mine doesnt work either...what switches did u check ?

 

? I'd appreciate a description of them, where they are at and what to look for. Hate to admit it, but I guess I'm clueless.

 

You will need to look up at the brake and clutch peddle shafts. You should see a little switch with a small 'pin' that should be touching the shaft. When you push the brake or clutch peddle the shaft will move away from this switch and break the ground....thus turning off (or not letting the Cruise to work if it's broken).
Good luck,

 

Thank you - This makes a lot of sense - I'll check this next.

 

Finally got around to checking the switches and found that the clutch switch was bad. I was a sport and for $11 each had them both replaced. Now it works, but only if I push the cruise botton with the lights off. I can set it with the lights on, if I push it initiatly with the lights off, but not if I try to set it after pushing the button with the lights on. Is there a reason it only works this way, maybe not using it at night, but that doesn't make sense either? Also, rechecked the lights and they all seem to work fine.

 

Can't say in this case, but most of the absolute weird electrical problems I've had in the past were all due to bad grounds -- so electricity found odd ways to run through the system. You might see if you have a loose or bad ground wire.

 

Is there one ground or several. How would you recommend finding/fixing the problem?

 

Hi guys. My cruise control / speed control light on the dash lights up when I push the cc on button but for some reason the cc doesn't work. It won't register a certain speed, increase or decelerate - nothing at all

I was searching and browsing around and found this post. Could this be my problem? I hope it is! I recently upgraded my tails with LED ones and the cc still worked then..UNTIL...I changed my 3rd brake lights to LEDs (2 assemblies: one on the wing and one outside). Suddenly, today, my cc won't work

Anyone who had this experience? Brake light bulbs were the culprit? Does this make sense?

 

You might try reversing the last light altering procedure and see does that cure the fault. If not then test the clutch and the brake switch independently.. I believe that you can bridge the two wires with a paper clip. If it works then its a bad switch right there.

 

@Hurdigurdiman - Thanks! Appreciate it.

To update the thread, YES the culprit are the FULL LED bulb upgrade. I installed load resistors on each of my LED 3rd brake lights and voila - the Cruise Control / Speed Control is back! Maybe it's safety feature of the pcar not have the cc function when your brakes are faulty. Makes sense! Thanks angain! :-)