VSS (vehicle speed sensor) on a W124 - PeachParts Mercedes-Benz Forum

ftav · #1 03-26-2007, 11:58 AM

Could anyone provide some assistance as to where the VSS (vehicle speed sensor) wire(s) on a late-model W124 can be found? I have a '95 E300 Diesel and would like to install a device that needs this signal to function. The owner's manual of the device says some cars actually have two VSS senders -- a low speed and a high speed. Any tips on where to locate these would be greatly appreciated. Thx.

-Frank

mbdoc · #2 03-26-2007, 12:05 PM

That car has 4 VSS's.

ONE for the speedo & 3 for the ABS traction system. all are A/C generators.

The speedo sensor may be a hall-effect....ie on/off/on/off

ftav · #3 03-26-2007, 12:41 PM

Are any of these in a location on the chassis that might lend itself to a wire-tap (i.e., preferably in the passenger cabin somewhere)?

Also, what does "A/C" mean in this context?

mbdoc · #4 03-26-2007, 12:57 PM

Inductive sensor that generates AC current.

The speedo would be the closest.

ftav · #5 03-26-2007, 12:58 PM

Incidentally I work in highway design and the device I would really like to install (and in fact already own) is a DMI or Distance Measuring Instrument:

http://www.jamartech.com/files/RAC_Plus_I_II_Manual.pdf

ftav · #6 03-26-2007, 01:01 PM

>>The speedo would be the closest.

Thx. I actually have instrument cluster removal tools from when I had a '93 W201. I don't have the car at the moment, but when I get to it and pull out the cluster, could you give me some description of what wire on the back of the speedo is the "target"?

If you could describe it either by color, location, or some other identifier, that would be great. I recently bought the "W124 Owners Bible" and was surprised there was no mention of it in there.

A264172 · #7 03-26-2007, 01:04 PM

I think they generate a current induced by the spining of whatever rotating piece of steel (wheel hub or driveshaft) they are positioned to monitor.

If you are looking to get speed based volume control... there may be a signal to the cruse control that would work best... unfortunatly I do not know what wire and where you could tap it...

A264172 · #8 03-26-2007, 01:34 PM

...I thought the spedo was mechanical...

ftav · #9 03-26-2007, 01:59 PM

I thought it was as well. Perhaps it is electro-mechanical and receives an electric signal which is then converted. I dont' know, but if anyone does, I have a $900 DMI just dying to be installed in my 124....

mbdoc · #10 03-26-2007, 02:18 PM

Speedo is mechanical...but the speedo has a speed sensor for the cruise control.

ftav · #11 03-27-2007, 01:41 PM

Could someone please provide either a description of what wire on the back of the speedo is the "cruise control speed sensor wire"? If you could describe it either by color, location, or some other identifier -- or a pic -- that would be appreciated and very helpful for those looking to install a component which requires this 'data'. Thanks very much.

A264172 · #12 03-27-2007, 02:00 PM

A quick look at my cruise control schematic has me thinking the output wire is (green/yellow), the power to the sensor is (black/red/violet) and the ground is (brown)

The output wire (green/yellow) goes from the speed sensor or hall-effect sensor (rear of instrument cluster, behind speedometer) to the X53 connector (right behind the instrument cluster) to the cruise control amp.

Oldbeaver · #13 08-10-2012, 06:04 PM

Quote:

Originally Posted by ftav

I thought it was as well. Perhaps it is electro-mechanical and receives an electric signal which is then converted. I dont' know, but if anyone does, I have a $900 DMI just dying to be installed in my 124....

Mercedes sends a mechanical signal from the transmission to the rear of the instrument cluster. Then, a electronic circuit with a Hall sensor located in the instrument cluster panel (behind), converts it to an electronic signal. Cannot say what kind of signal.

That is on a MB 300E 1989. Newer models may have the Hall sensor located on the transmission.

OldBeaver

Oldbeaver · #14 08-10-2012, 06:08 PM

Quote:

Originally Posted by ftav

Could someone please provide either a description of what wire on the back of the speedo is the "cruise control speed sensor wire"? If you could describe it either by color, location, or some other identifier -- or a pic -- that would be appreciated and very helpful for those looking to install a component which requires this 'data'. Thanks very much.

My manual says that you should seek for a Green/black wire.
Check for sure.

OldBeaver

J. M. van Swaay · #15 08-11-2012, 12:48 PM

Don't know about your make and model, but 94/95 124's have radios that change volume with vehicle speed. Accordingly, the VSS is available at the connector to the back of the radio head unit. Very simple to get to. I used this VSS as an input to an electronic first gear start module. Works great.

Can't remember which pin or wire color--some searching (or the FSM) might reveal the answer.....

J. M. van Swaay