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Cruise Control not working

24K views 9 replies 4 participants last post by  rudeney 
#1 ·
Hey everyone, I have recently puchased a 2001 C240. But I am having a problem.
The cruise control doesn't work on my C240. It didn't work when I bought the car but figured I wasn't doing something right. After reading the manual the cruise control operation seems pretty straight forward. Push up briefly to set. But when I do so nothing happens.

No warning lights are on.

I had a check engine light on last week for an 02 sensor, but that mysteriously turned off.
 
#2 ·
The first thing I'd check is to look at each one of the tire sidewalls and be sure they are all four the same size.

From there it's going to get expensive.

How did you know the CEL was an O2 sensor?
 
#3 ·
They all seem to be the same size,if they where different sizes would it disable ESP, but i will go out and check.

My fuel economy went to the shitter.
Well about 10 miles after buying the car and getting off the interstate the light popped on.
I was thinking it might just be from sitting for months.

So i went to Advance auto and got it read.
Something like Bank 1 sensor 1 and sensor 2.
But i was told it was the two upstream sensors.
 
#6 ·
Well... Those codes do not necessarily have anything directly to do with O2 sensor/s. It just shows that the O2 gets a too rich reading which is most likely due to problems more upstream.

In the case of these codes the most likely culprit is MAF. Either it is faulty or dirty. Other culprits could also be a vacuum leak or fuel delivery issues.
 
#8 ·
The MIL (malfunction indicator lamp, i.e. check engine light) will extinguish itself after three engine start/stop cycles when no errors are reported. Sometimes you can get transient errors caused by bad fuel, trash in the intake, etc. Other times, the error might be caused by a part that is beginning to fail intermittently. Just keep an eye on it.

Engine problems should not affect the cruise control. Check fuses 56, 57 and 62 (front fuse box, under the hood). I doubt it's any of those because you'd have other issues or ESP/BAS errors, but check them just in case. Also visually verify that your brake lights are working. There is a plunger switch on the pedal arm that can fail and if it does, cruise control is disabled. Again, I doubt that's it because you usually get a ESP/BAS error indicator. Finally, try setting it by pressing the lever down (either up or down will set it). If non of that works, then it's likely a bad switch.
 
#9 ·
I'm starting to notice my fuel economy going down, 15 in city. So i thinks it time for a engine tuneup.

For the cruise control, the fuses look good, brake lights work, and both directions of the switch dont work.
Is the switch hard to replace, do i need any special tools?
 
#10 ·
The switch is no fun to replace. You have to remove the steering wheel and the clock spring contact. It's not rocket science, but you need to know what you are doing.

On the economy issue, a failing MAF sensor is a common cause of this. If you are in the 100K mile range, it's time to replace the spark plugs, and while you're at it, you might as well replace the vacuum hoses on the MAF housing as they are likely rotten (vacuum leaks can cause bad MPG and idle problems).
 
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