Cruise control not working!!

[Shaunm41]

Not sure if this is the right section so sorry if it’s not..

I have a 2003 Mercedes CLK 270 and the cruise control isn’t working.. no matter what speed I’m doing, when I try to activate it, it just flashes 3 dashes a few times then goes off.. nothing else happens..

Any ideas where to begin?

thanks

 

[davidsl500]

Have you had any new tyres recently? Check tyre pressures all round would be a first step.

 

[Shaunm41]

Thanks for your reply..

I’ve just bought the car 2 days ago so not sure how long the tyres have been on..

I’ll check the pressure tomorrow.. it’s got AMG wheels on too, are they standard? It’s an avantgarde model..

Thanks

 

[John Laidlaw]

Speed sensors possibly
Did you get the car from a dealer?

 

[Shaunm41]

Yeah it was a dealer but they didn’t seem very good, I only gave £850 for it as a cheap run around / project to keep me busy

I do a lot of motorway driving so would quite like to have cruise control working

 

[EmilysDad]

brake light switch?

 

[Shaunm41]

brake light switch?

ahh yeah, I’ll check that..

Thanks

 

[davidsl500]

Cruise gets upset by wrong wheel / tyre combinations so check the tyres are the correct profile for the vehicle. Cruise also doesn't like new tyres on one axle and worn ones on the other. If you've bought it from a cheapo secondhand car dealer then they may have bunged whatever they had knocking about or maybe replaced one tyre. Some cars also have staggered setups so have a good look at each wheel/tyre combination! As EmilysDad, brake light switches also tend to fail on mercs for some reason, I replaced it twice within a few years on the R129 - mine got "sticky" and stayed on..

 

[Shaunm41]

Just had a look, tyres look reasonably new and sizes are as follows:

front: 255/35ZR18
Rear: 255/45ZR18

Are they the correct ones? Or could they be causing the cruise control to not work?

 

[malcolm E53 AMG]

What condition is your battery in if it’s not around 12.6V ancillary systems can start to shut down

 

[Blobcat]

Just had a look, tyres look reasonably new and sizes are as follows:

front: 255/35ZR18
Rear: 255/45ZR18

Are they the correct ones? Or could they be causing the cruise control to not work?

If they are 255/35/18 and 255/45/18 then there's you problem...
2" diameter or 8% difference so will stop cruise working

 

[RF man]

Just had a look, tyres look reasonably new and sizes are as follows:

front: 255/35ZR18
Rear: 255/45ZR18

Are they the correct ones? Or could they be causing the cruise control to not work?

From the Tyre sizes posted, looks like there is a diffent rolling radius between the fronts and the rears. I could imagine that upsetting the cruise control.

 

[Shaunm41]

Should I replace the rear tyres with the same as front? To be fair, it does look ridiculously higher at the rear than it does at the front..

 

[Blobcat]

Should I replace the rear tyres with the same as front? To be fair, it does look ridiculously higher at the rear than it does at the front..

Depends upon your rims, need to check the sizes as you might have staggered wheels - normally larger at the rear than the front.

 

[Shaunm41]

Depends upon your rims, need to check the sizes as you might have staggered wheels - normally larger at the rear than the front.

How can I find that out? All I know is there AMG rims and I’m assuming 18s

that’s all I know

 

[Blobcat]

How can I find that out? All I know is there AMG rims and I’m assuming 18s

that’s all I know

Stamped on the inside of the wheels on a spoke.

Also have a look in your fuel filler cap and see what 18” tyres could have been fitted

 

[Botus]

If they are 255/35/18 and 255/45/18 then there's you problem...
2" diameter or 8% difference so will stop cruise working

https://www.tacomaworld.com/tirecalc?tires=255-35r18-255-45r18

if this is a set up that was standard on some models they sold, there'll be a setting that can be tweaked using dealer diagnostics to tell your car how to do the maths so its happy....

can also impact ESP and ABS systems...

 

[mersum1es]

Isn't factory wheel size(s) written in UK registration papers?

CLK may have different sizes in front/rear, usually a,b,c,e classes have same size all around

 

[davidsl500]

You will have to take the wheels off and check out the rim width and ET for each one (stamped on the back of the spokes as said). An £850 car from a "not so good" dealer could have anything on it. I reckon it probably has a set of wheels / tyres that were knocking around off a scrap MB that has some tread left on them - cheaper than replacing tyres on the original set. Once you know Rim Widths and ET then its easy enough to work out which pair of tyres need replacing...

 

[Shaunm41]

Thanks for all the replies.. I’m not expecting a perfect car for the price and place it was bought from.. it was more of a cheap project.. hopefully, I’ll get all the little bits fixed and make my money back towards a newer model..

I will try take the wheels off over the weekend and have a look to see what they say.. the rims could do with a refurb to be honest so will look into that..

the engine and gearbox seem to be fine so that’s a start..