EGR/Resonance Control Module
 

Hi, New member with a new thread. Working on my 95 300d I've chased down all the vacuum control issues which lead me to a short in the electrical jack at the resonance cross over valves. I've noticed the resonance and pressure flaps never seem to operate and now I'm thinking the EGR/Resonance intake manifold control module may be fried (Probably by the aforementioned short.) My software doesn't disclose the location of the Control Module so that's my first question. Secondly, how to check it out. Do the control flaps oscillate like an idle air contol valve (in a gas car, not my diesel.) Thirdly, if I need a new control module where do I get one on the cheap? Thanks, Jack

I believe that the flaps change position with engine RPM. A code reader (if available -- most start with model year 1996) should tell you more about what, if anything, is damaged. I would replace or repair the shorted resonance valve first and see if the controller now works. Sometimes the designers put in circuitry that can detect a short circuit and shut down the electronics to prevent damage (and sometimes not). But it's worth a try before doing anything else.

As for getting replacement parts, try clicking on the "Buy Parts" link at the top of this page. Not only do you get a discount, but it supports this forum. Another source would be your favorite junkyard.

Jeremy

CEL (if lit up) blink codes should be available under your hood at the computer interface.

Press and hold button for 8 seconds.

Not sure the '95 (which is a W124 car) has a CEL. What/where is "the computer interface" and please explain the "blink codes."

Thanks for the input. No computer on a 95, just processor type control modules. Unfortunately no improvement after circuit repair. Local dealer can't locate module in their software and need the part no. Anyone have an idea as to the location of the EGR/resonance control module?

May have misspoke Jeremy. The 95 gassers (OBD1) have an integrated led/blinker at the scanner interface where you can read blink codes and retrieve emission faults. Started in 93 I believe.....w/o the integrated LED. Perhaps is only applicable to gassers?

*edit* - After further review, the 95 W124.131 also has a 16pin interface with integrated led for code reading. The codes have been posted many times; search Arthur Dalton's name.

My FSM includes that year...

If it is called the "Engine Systems Control" module, it is N16, located behind the battery (there's a thin black plastic panel behind the battery, a bunch of stuff behind it). The EPC may be able to get you a part number.

[Looking further...]

Ahh, how about "N37/3 EGR/resonance intake manifold control module" at location 18A? What, you don't know where location 18A is??? Actually, that's the coordinate on the schematic, doesn't help you. Let me look some more.

[Looking...]

Hmmmm, can't find it. What is your complete model number? 124 point something? 124.131? Looks like the manual isn't as complete as we might like. Anyway, I think "N37/3 EGR/resonance intake manifold control module" is what you want, just can't find it. It should be in the EPC, just can't figure out where...:confused:

Jeremy

Thanks for the effort Jeremy. You see my dilemma. Jack

I'm in a similar position - I would like to check the operation of the resonance flpas on my 95 W124 E300D - the wiring for the vacuum valves does go back via the engine wiring harness to the bulkhead connector on the RHS of the car (driving side UK, passenger side US). On the wiring diagram, the wiring passes through no other multi-plugs, so the control unti cannot be too far away from there - either in the bulkhead area, or under the dashboard at that side.

If you do find the module, would you be kind enough to post its location? - if I find it first, I'll post too.

Thanks for tip on Behind the battery location. Found three modules and overcurrent protection relay. By checking part #'s at an online parts site I found that the 016 545 9532 module is for EGR control and the 007 545 9632 is the idle switch. The EGR control is my main suspect and I'll check the wiring jack for continuity back to my switchover valves for the 3 flaps and egr probably this weekend. Stay tuned for developments...Jack

Had a chance to do some troubleshooting. By jumpering connections in the EGR module jack (guided by the schematic,) I was able to check the wiring for shorts and make sure I was getting power to the module. With the module removed I was able to run the engine so was able to check that the 3 intake manifold flaps and EGR valve were working. Jumpered the module pins to emulate fuction which it didn't but I wasn't 100% on that experiment. Been driving the car without the module in place and it idles a little better, runs about the same, using too much fuel. Heater doesn't work too well though. I'm pretty sure the module is shot and will replace it soon and give an update. Jack

Sad that I'm replying to myself but now to wrap things up.... Control module was only available from Germany but arrived in less than 2 weeks. Popped it into the jack and all's well. The heater is working again. The flaps and EGR valve work; once the car warms up. I've never seen the flaps working before and have recently fixed 2 vacuum leaks and the driveability per engine and transmission controls is very improved. Hoping for better fuel mileage. Idle seems a little rough but I haven't any reference to compare. Good luck with your EGR control module issues. Jack

Cazmont - thanks very much for the info you have given - extremely helpful - I'm about to spend the afternoon play... sorry, maintaining the E300D, so, I'll have a look and check to see if the system is working properly - I suspect not!

Here's how the resonance flaps work on my car;

The valve in the crossover pipe, I'll call X/O, and the valve in the manifold itself, I'll call 3/6.

The solenoid for the X/O valve is connected to the Yellow / Brown wire pair, and is the upper of the two solenoids when in the as installed position.

The solenoid for the 3/6 valve is connected to the Grey / Brown wire pair.

In the relaxed position with no vacuum, the X/O valve is closed - i.e. the crossover pipes remain independent for their full length.

With no vacuum, the 3/6 valve is closed, and the manifold behaves as an independent pair of 3 cylinder manifolds.

<2400 rpm 3/6 valve Closed, X/O valve Closed

>2400 rpm &
<3500 rpm 3/6 valve Closed, X/O valve Open

>3500 rpm 3/6 valve Open, X/O valve Open

I didn't reliably obtain any switching above 3800 rpm as has been suggested elsewhere, but, for me, that's quite academic; it's not an area of the rev range that I use often, or for any duration.

The sequence above seems logical enough, and so, I'll have to look elsewhere for an improvement in fuel economy. Perhaps I should just drive a little slower?

Hi N.C. Drive slower? I don't think so. I have a third flapper at the intake; the so called power valve. After getting all my flapper controls operating with a new controller I find the driveability way up. Much smoother operation of everything. Also much better mpg but no more power. That wasn't a problem before. It took about 150 miles of driving before everything settled in. Jack