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Max47 01-04-2009 03:25 PM

190e 2.6 1991 (M.B. Doc any help??)

I just get the w201 shop manual cd online. I need it to perform the troubleshooting procedure on my idle air control valve...

The m103 engine on the cd is for an older version 1987, at that time the OVP was supplying battery voltage to the IACV and they do not have MAS realy but fuel pump realy, the CSI was a 25 pin instead of a 50 some pin like mine.

On a 190e 2.6 1991 the the OVP (pin87L) feed the CSI and then the CSI feed the IACV, on mine the voltage isn't 12 volts, anyone know what the voltage should be.
Does the voltage change when the engine warm-up??
Anyone know or have the procedure to be perform on this model to check the IACV.
The IACV work well if I apply 12 V on it.

My other question is, my crank sensor read 500ohms (Hot or Cold) the specs say 680 to 1200 ohms... Should I replace it???

I' m after a Sudden Stalling Syndrom at -15 to -20 C


stevebfl 01-04-2009 03:52 PM

Duty cycle or milliamps

Max47 01-04-2009 05:28 PM

Outside temp -10C
Battery voltage = 12.5 volt

On/ off at the x11 socket

Between terminal 2 and 3

6 to 7 volts

at 80C
no on /off
reading = 10 volts

At 85C
9 to 10 volts

2 volts cold or hot

Is this normal???


mbdoc 01-05-2009 08:20 AM

On that & most M103's the idle control is measured as a duty cycle.

In other words the current to that valve is a constantly changing voltage.

Should have a 30% duty cycle at the valve.

Max47 01-05-2009 09:45 AM

duty cycle
Hi M.B. Doc

If mine do not cycle but has always 2 volts what is wrong CSI or MAS ???

Again the car stall only when the weather goes below -15/-20 C, engine temp at +/- 80C, deceleration before turning, hard to start after, have to wait +/- 15 minutes sometimes idle up and down when I start it back, put in gear stop boncing....

Thanks for your help


sbourg 01-06-2009 11:43 AM

To get a proper measurement, you either need an oscilloscope or a meter that reads duty cycle. If your voltmeter is averaging accurately, then 2V would be close to a duty cycle of 2/12 X 100 = 17%. However, that is assuming a lot. Best to get the proper meter.


Max47 01-06-2009 06:13 PM

Duty cycle meter
Hi Sbourg

I have 3 multimeters none seams to be able to read duty cycle.

-An old analog

-Blue Point model EEDM504 A

-Digital C-266

Any cheap dmm I could buy to do this duty cycle test ???

Thank for your help


Oracle12345 01-06-2009 06:57 PM

oscilloscope or the tools such as the modius by snap on can measure duty cycle

Arthur Dalton 01-06-2009 07:50 PM

Sears has a nice one for $20...Duty and Frequency...

Look it up inder DMM..if you can't find it, I will go out to the shop and see the model #..but I don't want to get dressed, so try Sears site first..

Arthur Dalton 01-06-2009 07:56 PM

Had another one in the house

Sears/Craftman Auto-Ranging DMM Model# 82139.

May be upgraded w/newer model...good tool for the $$$$$

See then on eaby for short $

Max47 01-07-2009 10:43 AM

Sears multimeter
Thanks Dalton for the info....

Sears Canada offer only Fluke meter :(:( No crafsman multimeter...

Sears US have the meter in stock but do not ship to Canada:mad:

So I think I'm stock with the Ebay process... Bid--- Wait---Pay + high shipping--- wait for delivery, almost a 14 days process:D

Anyone have one spare, if you ready to ship it to me, let me know....

Thanks again


Arthur Dalton 01-07-2009 01:55 PM

I did not know they did not ship to Cnd....

Try Radio Shack..they have then too... have an old Dwell Meter ???? can do duty with them too....Archieves has that info................

slk230red 01-07-2009 02:08 PM


Originally Posted by Arthur Dalton (Post 2071013)
I did not know they did not ship to Cnd....

Try Radio Shack..they have then too... have an old Dwell Meter ???? can do duty with them too....Archieves has that info................

I have a Dwell Meter....Thanks Arthur, I'm going to research this!



Originally Posted by LarryBible (Post 278207)
I've been meaning to mention this with every post I've made in this thread and continue to forget.

If you don't have a duty cycle meter, but you DO have an old dwell meter, you can substitute the dwell meter for the duty cycle meter when setting the lambda adjustment. You simply look for mid scale on the dwell meter. All a dwell meter is, is a duty cycle meter marked up in degrees instead of %.You will be looking for half scale which is 50% duty cycle. For example. For a four cylinder, max scale will be 90 degrees. This means that 45 degrees on the four cylinder scale will be 50% duty cycle.

I actually dug out an old Dwell meter and experimented with it. It was reading exactly center scale on my 300E pin 3. I didn't know whether or not to trust it at the time, so I bought the $27 meter. It confirmed that my lambda was set at 50%. This gave me confidence in using the dwell meter, but now I had the duty cycle meter so I didn't need it.

Hope this helps,

Have a great day,

Max47 01-07-2009 03:44 PM

Canadian Tire DMM
I find a canadian tire DMM on there site who do duty cycle, it was advertised at 59.99cdn here's the link: 1231359314548&assortment=primary&fromSearch=true

So I was ready to pay that price, I drive to the nearest store and pick one. When I get to the cash the girl say, you're lucky this item will be in sale tomorrow, I'll give you the special price 24.99 cdn, do you need a batterie with this?

Yes sure...:D:D

Here's the test I do with the DMM

Duty cycle test:

Outside temp: -1C

Engine cold:

diagnostic socket X11 (9pin round socket)
Pin2 ground
Pin3 red

49% no on/off

IACV: 72%/73.6% on/off

Engine at 50C:

Diagnostic socketX11:
62%/68% on/off

IACV: 72%/73.6% on/off

Engine at 80C:

Diagnostic socketX11:
62%/68% on/off

IACV: 72%/73.6% on/off

I do not unplug the IACV to do the test.

Since none of my shop manual or cd have the procedure for m 103 1991 2.6. the procedure in my book are for model without a MAS realy. The only thing I have is a wiring diagram for my model.

Who know what those result mean??

Anyone have the procedure for my model ??

Thank for you help


Max47 01-08-2009 06:24 PM

Duty Cycle + 16 pin tdc 190e 2.6 1991

I read a lot yesterday night on the board and find out that mercedes don't use the on time but the off time for duty cycle test.

True or False???

So I redone the test today, instead of using Pin 2 black wire and Pin 3 red wire from my meter I reverse polarity and I did the same for Idle Air Control Valve here's the result:

-Diagnostic connecter X11 (9 Pin Round)

Pin2= Red wire
Pin3= Black wire

Engine Cold:
50% no on/off

at the connector of the IACV

Pin2= black wire
Pin1= red wire

23.5%/24.5 %duty cycle

Engine at 50C:

23% / 28% on/off

at the connector of the IACV

Pin2= black wire
Pin1= red wire

25% / 26%duty cycle

Engine at 80C:

25% / 29% on/off

at the connector of the IACV

Pin2= black wire
Pin1= red wire

26.9% / 27.2%duty cycle

Is this result normal????

I also built a pulse tester following the design form Arthur Dalton.

I'am having a 16pin diagnostic connector next to the battery.

Here's the results:

Pin1= Black wire
Pin3=Orange wire
Battery(+)=Red Wire

Ignition ON
Engine OFF

Push the botton 2 sec. and release, the light start to blink...


If I refer to the table publish on the board, code 18 is "Current to Idle Control Valve is Illogical"

Do I perform this test the right way???

If yes what's next???

Do anybody know what the other pin in the 16pin diagnostic connector are for???

I have wire in pin6, pin7 and pin14 the other pin are empty.

Thank for your help


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