Cruise Control acting strange ...

[jasohal]

Hi,

I have a strange problem with the cruise control on my s320 '00 model.

I can set the cruise control at any speed up to 60 mph without a problem and it will hold the speed as normal operation.

However if I try and set the cruise control at any speed higher than 60 - the light segments in the speedo start flashing but the cruise does not hold the speed.

Why on earth it only lets me set the speed below 60 mph - I don't know- the only time I use cruise is when I'm on the motorway, and in which case I am always doing more than 60 ?

 

[McGreggor]

Have you fitted bigger wheels? I have had this problem after fitting 18" wheels, an inch bigger than standard. I reckon the cruise needs to be less sensitive to braking, or whatever is triggering in error above 60mph. I'm not sure if anything can be adjusted though, I'll ask my garage this afternoon when my car goes in.

 

[jasohal]

Yep - the wheels have been upgraded from the standard 16 " jobbies to some 19" Lorinsers..

I am keen to know the outcome of your garage visit ....

 

[Mambo]

Have you fitted bigger wheels? I have had this problem after fitting 18" wheels, an inch bigger than standard. I reckon the cruise needs to be less sensitive to braking, or whatever is triggering in error above 60mph. I'm not sure if anything can be adjusted though, I'll ask my garage this afternoon when my car goes in.

I've got 18's on mine too but my cruise works fine.......

 

[fwb44]

Hi,

I have a strange problem with the cruise control on my s320 '00 model.

I can set the cruise control at any speed up to 60 mph without a problem and it will hold the speed as normal operation.

However if I try and set the cruise control at any speed higher than 60 - the light segments in the speedo start flashing but the cruise does not hold the speed.

Why on earth it only lets me set the speed below 60 mph - I don't know- the only time I use cruise is when I'm on the motorway, and in which case I am always doing more than 60 ?

Just a long shot but have you inadvertently got the speed limiter set at 60 - tho' if you have, why you can go above 60 I don't know

 

[SeanO]

If it is not erratic (60 max all the time) it may need to be reset the software.
A trip to the dealers, I'm afraid.

PS. The lowest pernament speedtronic setting that can be set is usually 100/120mph, so I doubt its this

 

[Tigger]

Double check the tyre sizes...

That is exactly the problem a friend of mine had on his W210 E-class.

It should have had 235/40R18 all round. He decided to get (I think!) 245/35R18 or 255/35R18 on the rears. This was enough to put the rolling radius out ever so slightly which messed up the cruise control (cancelling at higher speeds).

 

[230K]

Hi

Yes this can even happen with new and part worn tyres of the same size and different make. Puzzled me for ages when i had the 230K C Class .

230K

 

[jasohal]

Thanks for all your replies ....

My feeling is with the tyre sizes too...

I have already changed the rears to 275/35 19's...
from 275/30 19's..

I will have to get the front's changed to 245/40 19's at the moment they are 245/35 19's.

Was going to do this anyway as I checked the tyre sizes against the Mercedes brochure and they were not right.

Still amazed at how sensitive these systems have now become !!

Will report back once the tyres are changed.

 

[SeanO]

Have also heard of low tyre pressure in one or more tyre causing Cruise problems.

 

[McGreggor]

Garage has said that my rear wheels are slightly bigger in diameter on the rears, and therefore rotate at a different speed to the fronts which confuses the car. You can measure yours from the centre cap star to the ground, front and back.

I think we need to know Mambo's tyre sizes to see what works, I'll post mine when I get the car back next week now (Needs new centre exhaust box at great expense, on order from Germany) Next time I need a new set of boots I'll get what Mambo is using and hopefully have cruise above 60mph again!.

 

[Mambo]

225/40 on the front and 255/35 at the back

 

[jasohal]

Guys just to give you an update....

Swapped the front tyres to the correct 245/40 19 size and guess what.....

cruise control now working a treat !!!

I guess if anyone else has similar probs a good point to start would be the tyre sizes...

 

[rs2000]

Hi,

I had exactly this problem with my W203 - brand new tyres on the back and 2mm tread on the front - all 225/50x16 Conti Sport 2s. Cruise wouldn't work reliably at speeds over 65mph (it kept cancelling itself) but when I replaced front tyres - problem solved! Dealer said they'd never come across this problem before!