Oil level lamp lit but oil level is fine

[mb280sel1985]

I drove on the highway yesterday 120 km/h and suddenly the oil level indicator lamp lit up. I took it off the road, stopped the engine for 5 minutes and manually checked the oil level with the stick. Oil was on or right above the maximum mark. The oil pressure needle is showing 2 or 3 just like before, so pressure seem fine. See the pictures.

Any idea what is happening? I've continued to drive it and the lamp is always lit. I've seen the oil level indicator lighting up on another w124 before, but it was very dim and fading in/out. That's not the case here, it is lit all the way, just as when you turn the key and all the lamps are checked.

There is absolutely no engine oil left on the ground after parking it over the night either..

I should mention I had 2 oil lines replaced after an accident. The engine lost all its oil when the oil line fittings broke from the crash. I bought 3 after talking to people on this forum, but the mechanic only needed two of them. See the pictures.

 

[gsxr]

The oil level light on the instrument cluster is supposed to have a 60 second delay, meaning the level sensor has to indicate low oil for over 60 seconds (continuoulsly) before the light should trigger. So, either....

1) The delay circuit has failed, and you are getting an "instant" warning, or...
2) The sender itself is faulty.

This can be a little tricky to diagnose unless you are handy with a volt/ohm meter.

 

[mb280sel1985]

Ok, so as long as the pressure needle and the stick shows oil I'm safe..

Where can I locate the delay circuit thingy and how to get to the level sensor sender unit?

Anyone happen to have the part numbers at hand?

 

[mb280sel1985]

The oil level light on the instrument cluster is supposed to have a 60 second delay, meaning the level sensor has to indicate low oil for over 60 seconds (continuoulsly) before the light should trigger.

Does this 60 second delay also apply when right after cranking up the engine? Is it not supposed to light up before 60 seconds have passed after starting her up? It lights up right away and stays there.

This can be a little tricky to diagnose unless you are handy with a volt/ohm meter.

No, unfortunately I'm not handy with a volt/ohm meter, but I can have a friend help me out.

 

[emerydc8]

Could there be a short in the lower wiring harness going to the oil quantity transmitter? Isn't that one of the wires in this harness? I think the lower harness had bad insulation just like the upper.

 

[gsxr]

Does this 60 second delay also apply when right after cranking up the engine? Is it not supposed to light up before 60 seconds have passed after starting her up? It lights up right away and stays there.

Yes, the 60 second delay should begin when the engine is started. So the light should not turn on until ~60 sec afterwards. The timing circuit is built into the fuel/oil/temp gauge pod ($$$$).

No, unfortunately I'm not handy with a volt/ohm meter, but I can have a friend help me out.

It's pretty simple stuff... here's a link to the FSM. Note that the R129 description is the same for the W124:
http://www.w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/119/18-3100.pdf

Could there be a short in the lower wiring harness going to the oil quantity transmitter? Isn't that one of the wires in this harness? I think the lower harness had bad insulation just like the upper.

Actually it would need to be open, not shorted. If shorted, the light should never turn on (assuming the gauge is ok). However, based on what he describes, even if the harness wire was open (broken), the light still should not come on immediately after the engine is started, it should be delayed 60 seconds.