Oil Level Lamp is lit, but level is OK on 94 E420
 

The Oil Level Light is lit in the instrument panel after replacing the coolant level sensor on the overflow tank. Maybe I touched or washed something sensitive under the hood...? Maybe it is a bad sender? Maybe my wiring harness is kaput?

I cannot find the sender location or the wiring location, or a connector for it, and I have the Manual CD! Is it on the CD, if so where? I found the wiring diagram, but without component location it is pretty useless to me.

Please help!

Oil level light activated by Coolant level sensor
 

I think it's more likely that something got transposed behind the cluster.
'Quick way to check...unplug the connector to your NEW Coolant Level Sensor
...Does the Oil Level Light now go out?

In the first Pictogram #71 is the Oil Pressure Sender (on the side of the Oil Filter
Housing.

In the second Pictogram # 44 is the Oil Level Sender (inside the Oil Pan)

What I'm "Guessing" is that (from my DeCoding of your information proffered)
the wire for the Coolant Level Sensor has been substituted for the wire from
#44.
Behind The Instrument Cluster.
[I do not even know if that's possible]

Because,What you're describing is the Oil Level Light responding to the Coolant Level Sensor (AND that Ain't Happening...Even in America.)

Compress Ignite,

Thanks for your reply and the clear diagrams. Where do you get those from?

Let me clarify: The Coolant Level Light works fine after replacing its sender. When the tank was empty it was lit, when I filled it the light went out. The Oil Level Light is on regardless of the coolant level.

Where do I look for the wire of the Oil Level Sender?

The oil level sensor is located down by the oil pump, obviously in a place where it can detect the level of oil in the oil pan. The sensor wire runs up on the right/passenger side of the engine block. You need to take off the lower oil pan to get to it, then a pretty easy job.

The oil level sensor, like the oil pressure sensor, alternator and starter, is not on the main harness but on the starter/lower harness which runs on the bottom right side of the engine. Lower harnesses have the same degradation problems as upper harnesses. If your recent work on the cooling level sensor was related it could be because you spilled some coolant on the lower harness. Or it could be just a random untimely failure.

http://mb.auto.pl/wis/w124/CD01/Engine/119/18-3300.pdf

deanyel,

Thanks for your reply and link. Not only did I spill some coolant, I followed it up by car shampoo and water, then a garden hose. I guess I have to wait until things dry out, then test the wire at component 2 in your link. That should determine if the fault is with the sensor or with the rest of the circuit. I am betting on the circuit.

Mercedes Benz Club of Russia's Electronic Parts Catalog
 

deanyel.
Thanks!


http://www.detali.ru/cat/oem_mb0.asp?TP=1

ANY CHANCE the sensor wire got "Knocked Off" the connection post
down at the Oil Pan during Cleaning Operations?

There is a GOOD CHANCE. As soon as the weather allows I will check the Oil Level Sensor Plug Connector and its harness. I found procedure 18-3320 "Testing oil level sensor" on the manual CD for diagnosing my problem. I have a love-hate relationship with this manual CD. It is pretty detailed and mostly unambiguous, but not searchable and oftentimes things are not where I would expect them to be.

Andras, it' possible the oil level sensor went bad and needs replacing. I recently experienced the same problem as you and replaced the oil level sensor on our 1995 E320. There is no need to remove the oil pan, but I recommend replacing the oil level sensor after you drain the oil for an oil change. The oil level sensor simply unbolts from the side of the oil pan ... at least on a 1995 E320.

Fred, this is an E420, different design than the 104.

I checked and took a few photos. It's my wiring harness, and probably unrelated to what I did. How much of a cost and job is it?

This is where I think the harness enters the passenger compartment.

"Biodegradeable" Wiring harness
 

You will want to familiarize yourself with this "Flaw":

http://www.peachparts.com/shopforum/general-information/128181-mb-wiring-harness-failure.html?highlight=biodegradeable+wiring+harness

That's the engine wiring harness. He's talking about the starter and ground cable harness. It doesn't go into the passenger compartment. It originates in the right rear of the engine compartment, behind the black box. It costs a little over $100 but repair is much less daunting than with the engine harness.

Thanks!
 

deanyel,

What do I know? (If I could, I'd be driving a diesel by candlelight)

It actually is the same insulation degradation problem - just a different harness, that tends to fail a little slower than the upper.