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W210 2001 E200k
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Discussion Starter #1
Hi guys,
Just wondering if anyone knows how the speed is taken for the speedometer? Is it taken from the front or rear axle?

Also, my needle does not match the digital electronic speed displayed on my instrument cluster, it is out by 1-3%, not that I care but just curious why it is happening.
 

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2001 C320 W203 Black on Black. 1997 E320 W210 Silver (RIP). 1995 E320 W124 Pearl Black.
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595 Posts
Mostly from transmission, follow speedo cable it will end up somewhere on the tranny.
 

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'01-E320 & 02-ST2
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Mostly from transmission, follow speedo cable it will end up somewhere on the tranny.
Well, if there was a speedo cable... ;)



I believe the speed input is from the VSS on the conductor plate (inside the transmission).

The mismatch is probably that your mechanical needle simply doesn't work properly. Mine had a lag 'n drag problem combined with a tick-y kind of bounce at some speeds. Luckily it was just before the warranty expired and the cluster was replaced.

If the needle still moves smoothly, but there is a lag in the speed, I'd just try and ignore it, remembering, of course, that you're traveling faster than the needle indicates.
 

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W210 2001 E200k
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Discussion Starter #5
Thanks guys, i will check exactly how much is it out compared to the digital one and then remember that is how much I need to add to the needle :)

I also wanted to know this as I wanted to fit one size up(profile) tyres to the rear to give it more comfort, so this will affect my speed too since it is taken from the transmission which drives the rear wheels.
 

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Thanks guys, i will check exactly how much is it out compared to the digital one and then remember that is how much I need to add to the needle :)

I also wanted to know this as I wanted to fit one size up(profile) tyres to the rear to give it more comfort, so this will affect my speed too since it is taken from the transmission which drives the rear wheels.
Be careful. If you vary the OD enough between front and rear, you will irritate the computer, triggering malfunctions and disabling safety systems. You will also wear out tires faster as you'll not be able to rotate them.

Good luck.
 

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W210 2001 E200k
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Discussion Starter #7
It will only be one profile up, so 10mm higher off the ground or 20mm dia difference.

But on that note, how does the computer/car know? There are no sensors/monitors on the wheels.
 

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It will only be one profile up, so 10mm higher off the ground or 20mm dia difference.

But on that note, how does the computer/car know? There are no sensors/monitors on the wheels.
Where did you come by that misinformation? There are sensors on each wheel that provide inputs for ABS and ESP systems, as well as the cruise control function.
 

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W210 E 240
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I have seen mechanics bugged by ABS light coming on with no error codes, turning out to be due to slightly different size tyres, so don't even go there!
 

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tagrobert, let's back up a second.

Is your car a 4Matic?

What size tires and wheels are you presently running? For the wheel, just diameter and width, but for the tires, width, aspect and diameter.

What tire size are you wanting to run on the rear, width, aspect and diameter?
 

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Our cars use all four wheels to determine the speed as follows:

* individual wheel speeds are compared an checked for plausibility

if no significant differences between the four are found, the vehicle speed is determined by left front wheel

* if wheel speeds differ significantly the computer determines whether the vehicle is cornering or if a malfunction occured

* if the vehicle is cornering speed is determined from the mean value of the front wheel speeds

* if there is one or more defective sensors the speed is determined by the highest wheel speed

* if fault messages are recieved for all four wheels, vehicle speed of "0" is displayed
 

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E320/E250 Bluetec Ford F350 6.7l
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Our cars use all four wheels to determine the speed as follows:

* individual wheel speeds are compared an checked for plausibility

if no significant differences between the four are found, the vehicle speed is determined by left front wheel

* if wheel speeds differ significantly the computer determines whether the vehicle is cornering or if a malfunction occured

* if the vehicle is cornering speed is determined from the mean value of the front wheel speeds

* if there is one or more defective sensors the speed is determined by the highest wheel speed

* if fault messages are recieved for all four wheels, vehicle speed of "0" is displayed
And I bet all of the above is checked like 100 times a second. Don't you love computers?
 

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W210 2001 E200k
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Discussion Starter #14 (Edited)
Where did you come by that misinformation? There are sensors on each wheel that provide inputs for ABS and ESP systems, as well as the cruise control function.
Haha, I didn't see any wires or sensors as such, only the low brake indicator..i must take another look.
I have seen mechanics bugged by ABS light coming on with no error codes, turning out to be due to slightly different size tyres, so don't even go there!
Hummm..this is the info that I have been waiting for, some experience on this topic :) thanks!
tagrobert, let's back up a second.

Is your car a 4Matic?

What size tires and wheels are you presently running? For the wheel, just diameter and width, but for the tires, width, aspect and diameter.

What tire size are you wanting to run on the rear, width, aspect and diameter?
No, not 4matic
I am running 15x7, 205/65 15(econo box stock rims), I want to put some 205/70 15 on the rear to give it slightly more cushioning for the passengers. I did this on my old car with hard suspension and it worked great, but that didnt have all this fancy abs, esp etc. I drive my car like a granny so no fast cornering performance driving, sound and comfort is my priority.
Our cars use all four wheels to determine the speed as follows:

* individual wheel speeds are compared an checked for plausibility

if no significant differences between the four are found, the vehicle speed is determined by left front wheel

* if wheel speeds differ significantly the computer determines whether the vehicle is cornering or if a malfunction occured

* if the vehicle is cornering speed is determined from the mean value of the front wheel speeds

* if there is one or more defective sensors the speed is determined by the highest wheel speed

* if fault messages are recieved for all four wheels, vehicle speed of "0" is displayed
Wow, cool, this is the info I was looking for :) thank you!
 

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216 with everything. 2002 SL500 with everything. 2009 SL500 with everything.
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The ABS is the base system, BAS and ESP work on top of the ABS. So if the message say all three the fault is with the ABS base system. The Speed signal is taken from the front wheel sensors.

Some cars will go into the limp home mode and lock up in second gear when the speed signal is missing, as the gearbox does not know what to do.

The BAS system on the 210 can have faults, the most common is the brake pedal travel sensor.

With an ESP fault there are 2 things, the lateral sensor that sits in the rear of the car that detects and the car is slewing, and the steering angle sensor in the steering column, the is so the car know what way they are pointing.
 
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