How to test the engine speed sensor on '93 300D?
 

I scanned the EDS system for the first time and found five stored codes including 007 starter ring gear speed sensor. After I erased the codes that was the only one that was still present (for now). How can I test the sensor before I replace it? A resistance check? An ac voltage output while the engine is running? What should be the specs?

When you pull the codes on the EDS system the engine must be running at the time the codes are pulled. If it isn't you will get the 007 code, I guess because since the engine isn't running the EDS computer doesn't see a engine speed signal. Try to erase the codes with the engine idling and see if the '007' re-appears. I'm betting it won't.

On an unrelated note a couple of months ago GSXR asked you a question about how your SDS clone was working, he wanted to know if you had tried it with your 400E and what systems it was able to connect with.

Have you used it with any other of your MB's? How's it working?

I'll try that but this thing barely runs after the glow plugs cut off. Hopefully that's related to the other codes I'll mention in another messasge.


This is the first MB I've tried it on and one that has the old style 8 or 16 pin plug in diagnostic connector socket. It took a while to figure out which holes to plug the four leads into (black, red, yellow, white) to get it to scan the various systems on this '93 300D. I figured out #1 is ground, #16 is power and my WIS told me #4 is for the EDS. Throught trial and error I realized #16 is only hot with the ignition on so finally I put the white lead there and I had to use a jumper wire with aligator clip to connect the red to the battery + cable.

I also tried to diagnose the airbag system as the SRS light doesn't work but the bulb is good. It said something like it couldn't find the SRS module in order to scan it??? Could that mean someone disconnected the module or disabled the SRS system? To access the module and check if its plugged in can I just remove the ash tray or do I have to take out the center console?

I've never tried to access the SDS control module for diagnosis but I know it's located in the passenger compartment on top of the transmission tunnel under the radio.

But I'm guessing you already know that.

I'd pull the radio and see if I could find the connector to the SDS control computer, its certainly possible somebody disconnected it when the got tired of seeing an illuminated SDS light.

Did you use the SDS clone on your 400E?

I just haven't got around to it yet. Wouldn't it be the same as this 300D or does that '94 have the 38 pin connector?

It has the 38 pin connector, it also has many more computers than your 300D. That car also has one of the first CAN networks and if the car has ASR its also one of the earlier "drive-by-wire" accelerator control systems.

Aftermarket scanners are not able to fully connect to the systems on the 400E, I'd like to know how well your SDS clone interfaces with the system in the W124 V8 cars.

I took out the center console and found these disconnected:
http://www.fototime.com/68209BDA196D68C/standard.jpg

Put them back together and now the airbag light works like it should.