w124 question re cruise control

[Badshot1uk]

Hi all,

I have recently purchased another TE, this time a 1991 300 24v.

I have a question re the cruise control.

It seems to work a treat if a little jerky?
It holds desired speeds and accerates/decelerates perfectly but just seems to be a lot less smooth in operation as opossed to holding the throttle down myself at any given speed?

Any idea's much appreciated

Cheers

Paul

 

[124coupe]

I answered your other post.

 

[Badshot1uk]

Hi steve cheers

I think we most both freqent both forums lol

I normally post on both as sometimes theres someone who may not go on the other ones.

Cheers again

Paul

 

[maiga]

I chose Cruise!

Thought I'd hijack another thread rather than start a new one...

I've just bought a well-used but fairly worthy '89 300CE with Cruise Control. This is second Merc after a very knackered 190E, but still made me decide I liked 'em. Coupe has no history or manual with it, and I've never driven anything with Cruise before...so I therefore ask;

1) How? How do I use it? Has a stalk with accel/up and deccel/down on rhs of steering wheel. Do I have to be doing a certain speed, and what to I do to switch it on/turn it off?

2) Why? Presumable good for dead straight US Highways/Autoroutes/Autobahnen when noone else is about, less so for crowded and roadworked UK motorways, and none at all for more twisty A-roads?

Any help appreciated...

 

[wscheffer]

Hi all,

It seems to work a treat if a little jerky?
It holds desired speeds and accelerate/decelerates perfectly but just seems to be a lot less smooth in operation as opposed to holding the throttle down myself at any given speed?

I believe Paul is not asking how to operate the cruise control! His question is once it it is engaged the cruise does not hold the desired speed with the same degree of smoothness that can be held manually

My W126 is doing the same thing, it is as if their is a leak in the vacuum line causing the drift in speed Approx. 1/2 mph in speed intermittently. I 'm sure Paul will correct me if I 'm wrong. The only problem is their is no vacuum operating the cruise control it is done electronically on the W126 and probably on the W124 as well.

My thoughts on this is a weak transister in ths cruise control amplifer causing the drift in speed but, I have not got around to changing it.

Any other thought as to the cause of this fault I too would also like to know!

 

[Mat_b]

My 1990 300TE is doing the same, holds speed but not smoothly as I can with throttle. An independant merc spealist told me cruise is linked to ABS and uses pulses from ABS sensors to regulate speed, If youve got a mixture of new and badly worn tyres it confuses system! Problem seemed to start when I put another set of wheels on. Though acording to Haynes manual there is a pickup on rear of speedo, and my speedo does jump very slighty as if speedo cable isnt turning smoothly, about to put 2 new tyres on which should even out ABS sensor pulses. Removing ABS module temporary would comfirm whether or not it controls cruise. anyone know if this is safe to do or will it damage other ABS stuff?

 

[television]

My 1990 300TE is doing the same, holds speed but not smoothly as I can with throttle. An independant merc spealist told me cruise is linked to ABS and uses pulses from ABS sensors to regulate speed, If youve got a mixture of new and badly worn tyres it confuses system! Problem seemed to start when I put another set of wheels on. Though acording to Haynes manual there is a pickup on rear of speedo, and my speedo does jump very slighty as if speedo cable isnt turning smoothly, about to put 2 new tyres on which should even out ABS sensor pulses. Removing ABS module temporary would comfirm whether or not it controls cruise. anyone know if this is safe to do or will it damage other ABS stuff?

If this was directly related to ABS, the lamp would have come on by now, I do know that there is a hall effect switch in the cluster that can go faulty causing the speedo to jump and intermittent cruise

 

[pj]

I had this problem with my 1994 W124 (E220 Estate). The speed sensor for the cruise is on the back of the speedo. The speedo needle was bouncy causing the car to be a little jerky with the cruise on. New speedo cable sorted it out. This was 18 months ago and no problems since. It had done about 120K miles then. The cable was about £45.

 

[The German Flower Pot]

hello

i too have a problem with my cruise controll

ive currently got 2 w124 coupes (e320 & a e320 turbo technics twin turbo)

the e320 cruise is on the wonk

the cruise works fine from the lowest speed of 30mph and works well upto about 50mph, then once it gets to 55-65 mph it judders and then seems to loose it and turns off

if im doing 70mph and click it on then it wont come on

if its working at 50mph then it will work up and down to higher/lower speeds

i was told that if you have the wrong tyres on it can cause this so i went from

235 x 45 x 17

to

225 x 45 x 17

and this made no difference

ive been told that a new cruise control unit from MB is around £500 and does not always work!

reading above about the ABS thing i know my brakes we new when i got it in october 2005 and im about to change the brakes again to lockhead vented (front discs & pads cost me £190)

so any ideas why its doing this?

in my 1st e320 coupe ive had the car sitting at 140mph+ on cruise control with no problems