1997 s320 oil lamp light on - PeachParts Mercedes-Benz Forum

lee polowczuk · #1 05-26-2013, 10:31 AM

My idiot light came on yesterday and it won't go off.

Car has 103k on it.

When I start the car up...no light...but then it comes on about 30 seconds later.

The car has no leaks and does not burn oil.

I had the oil changed at 100k...and the oil lamp light came on initially after the change, but then went out.

There is no FSS to reset.

Any ideas.... if its a sensor buried somewhere...i will more than likely pull the cluster and remove the light if it remains on... I am the type who checks his oil every time I fill up...

RichardM98 · #2 05-26-2013, 10:46 AM

I would probably start with a 'reset' of the CAN bus. If that doesn't clear the error then maybe the oil level sensor is faulty.

oldsinner111 · #3 05-26-2013, 10:57 AM

ussally the oil sender (pressure ) will go out first.you replace both oil level sensor and sender. If its check engine with low oil pressure it could be from running to thick a oil,and it shears off the teeth on the oil gearing.This clogs your oil screen.

lee polowczuk · #4 05-26-2013, 12:42 PM

what is the CAN bus? it's the 104 engine...so it's not very complicated

RichardM98 · #5 05-26-2013, 04:09 PM

Quote:

Originally Posted by lee polowczuk

what is the CAN bus? it's the 104 engine...so it's not very complicated

Mercedes was an early adopter of electronics and started using CAN bus in 1992 (earlier?).

A CAN bus car is one whose ECM (Engine Control Module) polls various sensors repeatedly to determine the state of things. Much like how a computer mouse is always checking it's location so when you click a button it knows what to do. When you turn off the engine everything is reset, then a few seconds later the ECU senses the error and turns the oil light on again.

The way to reset it is to disconnect the battery and wait about 10-15 min before reconnecting. Of course, be sure to have your radio code handy and some features (sunroof, windows, etc) may need to be resynced. This often doesn't work anymore than rebooting your computer solves a hard disk problem. But it is cheap so maybe worth a try. Also, sensor is pretty cheap for a M104.

Hope this helps some.

Gilly · #6 05-26-2013, 05:49 PM

I agree that it's probably just the oil level sensor, if this engine doesn't have FSS it would just be mounted to the side of the oil pan, relatively easy to replace. FSS cars got a bit more complicated with an oil level and condition sensor, can't remember if 104's had that or not, 96-97 was when that was just coming in.

Prior comment about CAN is way off from what CAN is. CAN is Controller Area Network, it was when many wires were eliminated by having multiple control units communicating over a common line. True MB was early in using this technology, but you would think of this more as having different control units "talking" to each other. For example if the engine temp is read in to the engine control module, and the climate control unit needs to know the engine temp, instead of a seperate sensor for the climate control, the climate control would get this information from the engine control unit. Climate control might also get the engine RPM from the engine control unit to determine if it's safe to engage the AC compressor, for example.

Disconnecting the battery to accomplish anything is almost always futile and you also don't need to "reset" a CAN data bus, it is just a communication line.

lee polowczuk · #7 05-26-2013, 07:24 PM

well... the light went out today... drove 100 miles no issues...

so it's a gremlin I guess... a couple of weeks ago that happened with the ASR.. light, but it went out on the next start.

i do have a car soft program... i just need to get a laptop with a serial port to make it work...

love the s320...i don't get to drive it much... but it drives like a dream

RichardM98 · #8 05-26-2013, 10:18 PM

Quote:

Originally Posted by Gilly

Prior comment about CAN is way off from what CAN is. CAN is Controller Area Network, it was when many wires were eliminated by having multiple control units communicating over a common line. True MB was early in using this technology, but you would think of this more as having different control units "talking" to each other. For example if the engine temp is read in to the engine control module, and the climate control unit needs to know the engine temp, instead of a seperate sensor for the climate control, the climate control would get this information from the engine control unit. Climate control might also get the engine RPM from the engine control unit to determine if it's safe to engage the AC compressor, for example.

Frankly, nothing you said is inconsistent with my prior comment. I gave a simpler answer since the OP was unfamiliar with CAN technology.

Gilly · #9 05-27-2013, 04:59 AM

QUOTE: A CAN bus car is one whose ECM (Engine Control Module) polls various sensors repeatedly to determine the state of things

This answer doesn't really explain what a CAN system is at all. How does this represent a CAN bus? Before CAN, lets say, there was, to simplify, a engine temp sensor. The engine control module "continually" polled the engine temp sensor, which to me would be better than "repeatedly". The CAN SHARES information on a common line between control units, this is very different than you are trying to describe. Hate to be argumentative but in this case I guess I am doing a good job of doing just that, sorry.

Gilly · #10 05-27-2013, 03:39 PM

Sorry, I wanted to expand on this a little, then the site went down for maintenance. I know this might be splitting hairs on terminology or just explanation in general.

In a case like this, and I am not sure at what level this model year was in the FSS system, but lets say the oil level sender info is picked up by the ECM. The information on the oil level could then be shared or tramsmitted to the instrument cluster via a CAN line. I know in practice that the later cars would actually transmit the data to the EIS, which acted as a gateway between the Engine CAN and the Interior CAN, these were kept seperate but again the EIS would relay pertinent info from the engine CAN to the instrument cluster.

This car I don't believe has EIS, so would think it has the early FSS system called ASSYST.