I apologize for the following newbie questions but I didn't get any response in the Benzworld so maybe I'll have better luck over here!

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Sorry for the newbie questions but I'm a little confused based on what I've read so far. I understand the functionality of the 16 & 38 pin connectors and that you have to use a scanner with Yellow, Black and Red test leads. Red = power, Black - GND and Yellow plugs into the appropriate pin to test a specific system.

On the 16 pin socket with the built in LED and a push button - that is a source of my confusion. When you read the blink codes from this LED, what system(s) are the codes for? Is it reading the DTC from one system or for ALL systems? The tables I see are: CFI, MAS, SRS & A/C.

I've downloaded the DTC codes, procedure on how to read and reset. Right now, I have two codes: 15 & 16. The trouble is, I'm not sure which table I should be looking at. By process of elimination, I think the two codes I have are for the CFI system. Please correct me if I'm wrong!

CFI (cont fuel injection system) Table
Code 18 - Current to idle control valve is illogical.
Code 16 - EGR switchover valve, open or short circuit.

Thank you kindly.

1990 300E, 124.030, chassis 103.983

This thread has a lot of links and a lot of information you can use. Download the pdf attachment I've linked. You should find your answer in there somewhere.
E320 16 PIN DTC Charts inc. pin 8, pin 14

Which pin are you getting the codes from?

Attached Thumbnails

 

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

At this point, I'm not using ANY pins. I'm simply pushing the button and reading the LED blinks.

What i'm unclear on is what system am I reading by pushing the button?

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1990 300E
124.030
chassis 103.983

Ok, I've found the answer I'm looking for.

Copy/paste

Arthur Dalton E320 16 PIN DTC Charts inc. pin 8, pin 14

If the car has a Built-in led/sw , it only address the DM module.. [ Diagnostics Module] ..and that module [ N/59] is nothing more than an Emmssions Monitoring/ Fault Detscting Module . If that module detects an emmission fault , you can go get that basic info with the built-in button.

Any of the actual Engine Mangement and chassis running gear modules [ HFM/EA/CC/ASR/ Etc]... have to be gotten from the other sockets and require a scanner or , at the least , the home-made Led/Sw tool.

The only reason for the DM and the CE lamp is to notify a warning that an Emmissions mandate fault is present in the cars emmisions system and it will not pass an emmissions testing and should be addressed..........
The cause of that fault can come from one of the other management systems , but if other faults in the other modules will not effect the emmissions standards, it will not show up in either the CE lamp or the built-in led.
So, if one does have a couple of codes w/PB , they want to further investigate the cause/s by going into the other modules.
An example would be a code on the DM that simply states "Igniton Fault'... ...b/c it has talked to the HFM module and the DM knows that a mis-fire in the Ignition will effect the cars Emmssions...now , by going into the HFM module, you can get a more specific ignition fault with the Flash tool, [ like coil # T3 output ] and if you actually had a HHT digital scanner , you could get an even more refined Ignition fault specific.
These late OBD1 systems do not get the credit they rightfully are due, and although the were crude in comparison to the OBD2 generation, they cetainly were cool for that time...and I have personally seen hundreds , [ if not thousands] of broken cars right here on this Forum in my 10 years that got fixed with the aid of that diagnostics capability..even just the built-in LED gave some direction, never mind the Homemade one or a digital scanner.
As one looks back, it was crude , but at that time , it was the balls....

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1990 300E
124.030
chassis 103.983