W210 Cruise Problem

[GordonTarling]

Thought this happened a few weeks ago, but today's trip has confirmed it. The cruise on my 2001 W210 is acting very oddly - it will engage and stay engaged for quite some time then, for no obvious reason, it'll drop out. Once it starts playing up, it'll drop out intermittently, but fairly frequently. On some occasions using 'set' does absolutely nothing and the cruise will only engage again by using 'resume'. At one time on today's trip, I had been cruising at erm 75mph when it dropped out - I used 'resume' to re-engage it and it took the speed up to 85mph and then dropped out. I've searched the forum, but can find no-one else who's asked about a snag like this! At first, I wondered if it could be the infamous brakelight switch, but I'm more inclined to think it's either the column switch or the speed sensor. Anyone got any better ideas?

 

[Dragon]

It happened to my 2001 W170. Have to stop by layby to switch off engine and restart again. Something to do with the microprocessor in the ECU. I thought it something to do with an under rated non-MB battery. It hasn't bother me ever since.

 

[PeterE320Cdi]

Mine started working after I fitted a new battery.

 

[GordonTarling]

Thanks for the ideas chaps! I did fit a new battery back in, um, January I think, but it was a Bosch one and I can't think how that would affect the CC if it still starts the car OK.

 

[television]

Thanks for the ideas chaps! I did fit a new battery back in, um, January I think, but it was a Bosch one and I can't think how that would affect the CC if it still starts the car OK.

I have looked but found nothing,,most cruise controls drop out with a momentary loss of a speed signal,,Have you got an indie with star

 

[PeterE320Cdi]

I was surprised too when mine started working as it had not worked for a long time before the car showed signs of a flat battery. The explanation I received was that the car shuts down non-essential functions to conserve power when it senses a low battery. I have no idea if this was true or not.

 

[mr. shr]

I was surprised too when mine started working as it had not worked for a long time before the car showed signs of a flat battery. The explanation I received was that the car shuts down non-essential functions to conserve power when it senses a low battery. I have no idea if this was true or not.

I wonder whether the act of disconencting and reconnecting (in your case old batt for new) somehow re-set things?

Not saying that's the case, I'm just thinking out loud.

 

[television]

I wonder whether the act of disconencting and reconnecting (in your case old batt for new) somehow re-set things?

Not saying that's the case, I'm just thinking out loud.

If the standing voltage of a battery is low, the what we call starting blips. These can acure, this is when some ECU's cant re set.
This battery is newish and the fault happens while driving so not battery in this case

 

[Dieselman]

I have looked but found nothing,,most cruise controls drop out with a momentary loss of a speed signal,

This would be my guess, along with brake light switch.

 

[GordonTarling]

Thanks chaps - most helpful! Now, does anyone know where the speed signal is derived from? My speedometer has been 'stepping' rather than moving smoothly for some time now, I wonder if the two faults are caused by the same thing?

 

[television]

Thanks chaps - most helpful! Now, does anyone know where the speed signal is derived from? My speedometer has been 'stepping' rather than moving smoothly for some time now, I wonder if the two faults are caused by the same thing?

yes this could be linked, I am taking one more look

 

[television]

I know that your car is the 210226 nothing on cruise at all,well if there is I cant find it. I will take a look at the earlier car in the morning

 

[Ade B]

The cruise on my C124 would intermittently surge and occasionally drop out - its worked perfectly since changing the very worn rear tyres. Not sure if the two are related...


Ade

 

[Dieselman]

Thanks chaps - most helpful! Now, does anyone know where the speed signal is derived from? My speedometer has been 'stepping' rather than moving smoothly for some time now, I wonder if the two faults are caused by the same thing?

Absolutely.

Firstly check the connection onto the back of the instruments cluster. The speed signal is a derivetive of the wheel speed sensors, but not sure if it's a single unit or a comparison of all four.

 

[Diesel Benz]

The cruise on my C124 would intermittently surge and occasionally drop out - its worked perfectly since changing the very worn rear tyres. Not sure if the two are related...


Ade

The car in concern could get confused from very differently worn and different size tyres but for a C124 it sounds odd to me.

 

[Dragon]

Mine started working after I fitted a new battery.

The state of the battery has anything to do with the Cruise Control? I had an argument with my battery supplier. He said it not true. He said the car still goes if I have started the engine and disconnect the negative terminal of the battery. Or what he said is a lot of Bull?

 

[GordonTarling]

Thanks again chaps! FWIW, I fitted new rear tyres about 3 months ago, so I don't think it can be that. Front tyres are partly, but evenly worn. I'll check connections at rear of the instrument cluster as soon as I can. Failing that, I guess it's a trip to the dealer to see if they can somehow check the speed signal.