Hi guys,

I cannot get the ELR to flash any error codes on a 95 E300D - Ive tested everything else - and I get results but the pin 4 (diesel system) does not flash codes no matter what I do, 4 second hold, 20 second hold key off key on engine start - nothing works - bad ELR module you think?

I checked the OVP and its the new type with 2 fuses on top which are intact, Ive got a working tach and klima, ABS etc. except this stupid ELR module, anyone have a wiring diagram I can use to test the ELR socket pins for power, ground and other pieces

the ELR does not control idle revs either and I hate the vibration it causes when the A/C compressor switches on.

a little update - that I checked everything (engine wiring has 2007 sticker on it) the body plug near the ELR is 14 pin and not 12 pin as the manual says. The ELR module pins are a little different from the one the online 124 manual showed me, but made sense out of the printing on the module itself.

Anyhow, the main problem is that Ive checked all power, ground and other sources - all work out to be in spec - then why doesnt my car raise idle speed when the A/C compressor kicks in.

any idea where I can borrow a module for testing to ensure that its actually the culprit

well as no one is pointing me in any direction Im going at it myself, so far - Ive got the thing to work - it was the wrong connector on the pump.

well, the engine starts super - and idles at 950 revs, and they do not drop no matter how long I drive with the temp needle in the middle. 80 degrees or so. When I remove the ELR plug on the pump the idle drops to 500.

The unit only flashed 2 codes once and then went silent. The codes are
2 (rpm sensor)
3 (ELR coolant temp sensor),

I could not get code 3 again no matter what, I just got code 2 flashed over and over, and now its silent no codes and a 950 rpm idle. I do notice that the rpm sensor has been changed at some time, as the wire looks pretty new and its not clipped into the ear by the oil filter.

Do these ELR units - need a specific sensor e.g. you cannot swap a VDO one for a siemens, or AB elektronic, as the ELR module would be looking for a specific kind of rpm sensor..

anyone?

I did some further tests at the ELR plug on the pump. its showing 14V and drops when I blip the throttle, the manual tells that this means the rpm sensor on the bell housing is bad or the wiring is bad.

the sensor is perfect, the rpm meter, A/C and everything related to the tach works. All I can see in the service manual is that there are 3 different brands of sensors all having different resistances. Now I dont know which one is compatible with my car.

According to the way I read the MB docs for test step 4.0 the desired behavior is 11 to 14 volts and a drop when you blip the throttle. It sounds like at least that portion is working correctly for you.

My ELR isn't showing any codes either and according to the MB doc it should at least show a code of 1 if there is no problem.

Did you ever get yours figured out? Can you explain what you mean by the wrong connector on the pump in post #3?

__________________
'82 300D - Light Ivory, 2nd Owner (Back in the wind April 2013!)

'95 E300D - White, grey interior. (Suffering from stuck/broken glow plugs)

Deuteronomy 22:4-
"Thou shalt not see thy brother's ass or his ox fall down by the way, and hide thyself from them: thou shalt surely help him to lift them up again."