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Cruise control / Tempomat problem

13K views 22 replies 11 participants last post by  aam 
#1 ·
Hello,

Cuise control works perfectly until 90km/h (dunno how to convert it mph)

after that it disengage or deccelerate until 90km/h.

Someone experienced the problem?

Any advice ?
 
#3 ·
poms2000 said:
Hello,

Cuise control works perfectly until 90km/h (dunno how to convert it mph)

after that it disengage or deccelerate until 90km/h.

Someone experienced the problem?

Any advice ?

If you don't mind I would first like to ask if have you read the owner's manual and fully understand how the tempomat should work?

My second question is what exactly do you mean by "after that it disengage or deccelerate until 90km/h"? Can you please describe the problem a little more in detail please?

90km/h is approximately 56mph.

Thanks,
Erik
 
#4 ·
No intention to steel this thread, but I got a similar problem with my tempomat.. 80% of the time not working - 20% working...

The mb technician told me that there is a small processing unit (in the engine area) that controls the tempomat - which found half-melted due to some short-circuit, or something... He suggested that it's not worth the cost of the spare part, ie region of 800 euros (usd 1000)..


Pleased to hear bobterry's (or anyone else's) thoughts!!

George

++
 
#5 ·
RE

ErikFinn said:
If you don't mind I would first like to ask if have you read the owner's manual and fully understand how the tempomat should work?

My second question is what exactly do you mean by "after that it disengage or deccelerate until 90km/h"? Can you please describe the problem a little more in detail please?

90km/h is approximately 56mph.

Thanks,
Erik
Hello,

Cruise control is working fine till 90km/h but if i'm riding at 120 km/h for exemple and that i engage the cruise control it does not engage.
Thus after 90km/h cruise control is not working but before 90km/h it is working fine(i can accelerate,deccelerate,all functions working).

I really don't know why.
If someone experienced same problem please give feedback.
 
#6 ·
:(

Hello,


If someone got any idea about this problem i will appreciate his/her help.

I really dunno why the cruise control won't work after 90km/h.

Some told me that maybe it's the rims(i have changed them,was 17 inch oem before and now 18 inch R230).

Is there any sensor at front wheels?

How can i check it?
 
#7 ·
detailas said:
No intention to steel this thread, but I got a similar problem with my tempomat.. 80% of the time not working - 20% working...

The mb technician told me that there is a small processing unit (in the engine area) that controls the tempomat - which found half-melted due to some short-circuit, or something... He suggested that it's not worth the cost of the spare part, ie region of 800 euros (usd 1000)..


Pleased to hear bobterry's (or anyone else's) thoughts!!

George

++
Hey George: the diagnostics for the cruise control on an SL320 are comprehensive and detailed, so reading codes should be very helpful in diagnosing your trouble. Since your car is later than '95, an advanced scan tool is required, of course -- no $1 LED to use here.

Note to poms2000: sorry, but I don't think I can be of help. Still, you really need to state the model and the year of your car when asking most technical questions.
 
#11 ·
poms2000 said:
Hello,


If someone got any idea about this problem i will appreciate his/her help.

I really dunno why the cruise control won't work after 90km/h.

Some told me that maybe it's the rims(i have changed them,was 17 inch oem before and now 18 inch R230).

Is there any sensor at front wheels?

How can i check it?
just a thought if you haven't thought and done so already: if you have the option to put the OEM wheels back on and then take it for a spin and see if the cruise works or not..?
But I don't know how you can reset any possible fault codes and if you should do this before trying with the OEM wheels or not... I just know that people have had issues with the ABS if the wheels are not of correct size.. Not sure if that would affect the tempomat though...
 
#12 ·
Yup already put the OEM rim and same problem with cruise control.

Maybe something wrong with the front wheel sensors but i don't know where it's located to have a look at.

What is surprising is that it works perfectly till 90km/h(56mph) and after that it disengages.
 
#13 ·
I just noticed precisely the same problem with my 1996 SL500. I can't engage cruise control driving above 90km/h but below that speed it works fine. I read on another post that the tyre pressures need to be even. Try this link:

http://www.benzworld.org/forums/r12...rol-diagnostics.html?highlight=cruise+control

I usually have my tyres at 31 on the front and 33 on the rear. The wheels are 18 inch and I've never had problems with cruise control before, even at speeds above 100km/h. So something must have gone wrong just recently.
 
#16 ·
Well,


after that my BAS/ASR light went on i went to a MB dealer and bought a brake switch.

This correctect the BAS/ASR light but also the cruise control problem!!!!

I think that maybe the brake switch was already bad and went worser till the BAS/ASR light came on.
 
#17 ·
Great news Poms! Thanks for posting! How much was the part?
If I recall correct, the tempomat won't work if the rear brake light bulb is out. So the tempomat functionality appears to be very much related to the brakes. They must share some common circuits. I don't know and I don't have the chematics, but I recall this from the past. Brake light bulb out and Tempomat wouldn't get cancel signal if brake pedal touched? And thus tempomat goes INOP?
 
#18 ·
ErikFinn,

the part cost me 16 €,the brake switch is really cheap and can be easily changed.
It's located between steering wheel and brake pedal .Just a philips screwdriver and it's done(10 minutes work).

Even if you rear brake bulbs are ok the brake switch can be defect(that's what happened to me,bulbs and brake power were ok)

As you said they must share same circuit.
 
#20 ·
With tyre size it is not only the width but very much more importantly the overall diameter.

Consider the chart below, you may have 18 inch wheels but what you put on them and the overall final diameter can have a very great effect. (if this combination was put on a vehicle running in 4x4, the transmission creep would most likely do a lot of damage) It would more than likely confuse an electronic speed control system.

click to enlarge
 

Attachments

#21 ·
RedLiner

You are correct as usual.
When you drop the profile hight.
You must raise the the tread width.
275 x35x18 is where you are sop oust to install to kip the diameter
balanced.

To put it in an other way.
When you drop the panties, you must raise the bra..........
End of story.

aam.
 
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