M102 / M103 CIS test cables
 

G'day Folks,

A big blow has been dealt to my personal wealth again - this time buying a test cable for measuring the current drawn by the air idle control valve on my M102.

Looking at the cable (after purchase) I got that WTF sinking feeling => "could have done this a bit cheaper I guess".

This is often the way with Mercedes special tools.

My reason for buying the bit or wire (at silly money) is mainly due to lack of confidence when it comes to all things electrickery - but I guess this is one way I'll force myself to learn!


Whilst I'm not exactly happy with the purchase I guess one way to make myself feel better is to "show the secrets" of how it was done so that perhaps others can benefit from the knowledge.


First off though I'm going to bore you all with some pictures of the most expensive bit of wiring I've bought in my life (I think even my low oxygen spun on the inner thigh of a virgin loudspeaker / home HiFi cables worked out cheaper per mm!) =>

(Drum roll - here it is)

102 589 04 63 00

http://www.peachparts.com/shopforum/...1&d=1443710962

(Made in Hungry in 2013 with plug ends that still have "Made in W. Germany" stamped on them. Just goes to show how many of these little beauties have been sold)

http://www.peachparts.com/shopforum/...1&d=1443710962

http://www.peachparts.com/shopforum/...1&d=1443710962

http://www.peachparts.com/shopforum/...1&d=1443710962

So as you can see this is just a bit of heat crimped wire with three plugs on it.

This isn't a surprise to me as it is quite clearly shown in the FSM the problem was that I didn't know which plugs were fitted on the bugger.

So for the record the plugs on the end are

0085450828 => goes to multimeter / ammeter

0085450928 => connects to plug on car loom

0115457128 => connects to air idle control valve (2 pin version)

Please note this is only good for the 2 pin version of the air idle control valves on the later KE CIS systems

So OK perhaps some good can come from this?

From what I can see at the time of typing the plug part numbers listed above are all available at the dealership.

You could also get the plugs from a scrap yard.

You could also piss about with crocodile clips and bits of wire and match sticks trying to get a decent connection as I'm sure many do. Problem with this approach is that you might short out the bits or bugger up more stuff on your car - I dunno.

Despite the recent fleecing I still think plugs are best

For the sake of clarity...
 

...here's how you fit the cable.

Remove air filter

Unplug wire from air idle control valve

http://www.peachparts.com/shopforum/...1&d=1443711769

Plug in test wire on air idle control valve and connect wire on the car to the other end

http://www.peachparts.com/shopforum/...1&d=1443711769

You've then got two plugs to somehow fit to your multimeter / ammeter

http://www.peachparts.com/shopforum/...1&d=1443711769

For this there's another test wire (I guess) but because it can be pulled away from the car and away from harm I'm going to use some old fashioned 4mm banana plugs so I can secure some crocodile clips to the ends.

http://www.peachparts.com/shopforum/...1&d=1443711769

Everything is going to be taped up so I can't ground this connection with the chassis by accident.

Note:-

This cable is essentially disconnecting the existing wiring loom so that an ammeter can be connected in series

If you leave the test cable in place with out a connection to the ammeter / multimeter then the idle will be high => because the control valve is effectively disconnected. Connect the measuring instrument - make a reading - and the valve works (hopefully).

The proper clips for these are cheeep on our favorite auction site.

hook clip is the quickest way to find them.

They come all the way from just a clip to a variety of ends, alligator to meter plug ins.

They work GREAT !!

Yep I have those clips as well but I use those for the air flow sensor potentiometer measurements (parallel) and the test cable with crocodile clips for the current (series) measurement on the air idle control valve.

I've also got two little pins to stick in the X11 socket with crocodile clips to make the lambda / O2 sensor measurements.

Very often on ebay groups of 5 or 10 of the same clip can be had for not much more than one if you hunt thru the listings

This will work for the EHA testing, correct? :confused:

If so, I need to order one

Sorry I don't know for sure.

I'll see if it fits on my EHA tomorrow (when it is light). If you were to measure the electric side of the EHA there is some information on the internet to what people think it should be - and these values are given in terms of current - so you would need to connect in series (like this test lead set up)...

...I'm a bit concerned about the internet information though as I'd like to check back with some FSM data first but I can't find any / haven't found any yet for the EHA.

Hitter:

That is the cable for the EHA.

Excellent, thank you for the reply!

It does indeed fit on my EHA - so that's good to know.

Has anyone got the FSM specifications for the electric side of the EHA?

I can't find the bloody information in either the W124 or W201 FSM

PS Hit Man X

Save some money - buy the plugs (part numbers given above) and make your own cable

Glad to know Im not the only one who cant find EHA specs.

Found them!

http://www.startekinfo.com/StarTek/outside/12264/Program/Engine/103/07.3-0121.pdf

Pre-1990

Page 109 and 116 in the PDF linked above

Post-1990

Page 147 and 160


{It is nice to see the documentation is so easy to follow for these awkward arse buggering systems}

And finally...
 

...here's the wiring!

If you are making up your own plug and cable set then you might like to know how the pins on the plugs are connected.

http://www.peachparts.com/shopforum/...1&d=1452700484

Normally the two plugs (0115457128 and 00854509289) are fitted together.

If you look on the plugs the pins are labeled #1 and #2. Normally #1 on one plug goes to #1 on the other (and #2 to #2). For the test cable because you are measuring current you need to split one line to the "third plug".

Mercedes have chosen to split the wire between pins #1. So pin #1 from one plug goes to one of the (un-numbered) pins on the third plug. And pin #1 from the other plug goes to the other pin on the third plug...

Clear as mud?

If you loop the ends of the third plug like this =>

http://www.peachparts.com/shopforum/...1&d=1452700484

Then you are back to the old situation of pin#1 on the loom going to pin#1 on the air idle control valve / EHA. (And pin#2 is left alone and not messed with) So with this you are back to how it is wired on the car.

If you have a loop (red wire in picture above) then it is easy to use a current clamp multimeter to measure the current and any influence from a multimeter is removed from your measurements: My auto ranging multimeter would stall the engine when I connected it to measure the current - so I got a current clamp multimeter to do the job for me.