...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.



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 =>



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.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!