Every now and then the "display defective" warning on my 96 E320 will come on when starting. It has a picture of the rad. Coolant level is OK. Is it just telling me that the sensor for coolant level is busted??

 

change the washer bottle sensor, had the same problem with my 96 E320
dont know why it shows symbol of radiator nothing to do with it.

 

my 2002 e320 shows 2 malfunctions when i start up.
display defective
and tele aid SOS.
does anyone have any idea what these indicate?
thanks

I have a 2002 E320 and a few weeks ago when I started the car I got the message on SOS/Teleaid saying not working to visit workshop. The red SOS light by the rear view mirrow wasn't on either but I tapped it a few times and the light came on and I cleared the malfunction and so far I haven't had the same issue. When I talked to my MB Service Advisor I told him what happened and he said not to worry about it that maybe the SOS/Teleaid sensor was going bad but since I don't use that service/SOS Teleaid not an issue. I think he could be one of those electrical gremlins that pops up every now and then. Personally I wish I could just have the SOS/Teleaid disabled from my car since it is just one more thing to go wrong. I have no plans to ever utilize it.

 

I had the same thing one time. I restarted the car and the warning was gone.

 

missing pixels

i have noticed some missing pixels in the display. these are the ones where it says P for Park, D for drive etc.
I wonder if this is what triggered the defective display message.
I am not sure whether to live with the missing pixels or to change the display.
i guess that will depend on the dollars to pixel ratio.

 

i have noticed some missing pixels in the display. these are the ones where it says P for Park, D for drive etc.
I wonder if this is what triggered the defective display message.
I am not sure whether to live with the missing pixels or to change the display.
i guess that will depend on the dollars to pixel ratio.

No it is not related to lose pixels. In the sticky, there is an easy fix to restore the pixel. Have a read and see if you think you can handle it. If you search the forum, there are plenty of advises on this topic as well.

 

loubapache, that's a very detailed and intelligent analysis! Thanks a lot for explaining how that works, and what is going wrong when it doesn't.

 

Do not ask me what got me into looking at this. And it drove me crazy until I found the circuit diagram.

So if it measures 1.9 V, it should say check washer fluid level; if it measures 2.6 V, then it should say check coolant level. However, often the messages are not telling exactly what is wrong. In this case, what if the voltage is between 1.9 V - 2.6 V, 2.6 V - 3.5 V, and 3.5 V -8.0 V? Somehow some contact resistance can mess up this whole design. They might be just better off using two separate circuits.

The washer fluid level sensor is easy to clean and check than the coolant level sensor.

However, the washer fluid level sensor is more than twice the price than the coolant level sensor.

In the older models (W124), one can simply unplug the coolant level sensor but not in these W210's. If you unplug one of the two sensors, it says display defective, LOL.

The messages for the scenarios I posted earlier are:

Voltage---------------------------------------------------------------Message

1) both working (~ 3.5 V)-------------------------------------------No message
2) washer level sensor working only (~ 2.6 V)----------------------Coolant Check Level
3) Coolant level sensor working only (~ 1.9 V)----------------------Washer Fluid Check Level
4) Both not working (0 V)--------------------------------------------Do not know but probably Display Defective
5) Open circuit (8.0 V)------------------------------------------------Display Defective

So in my case a couple week ago, the Coolant Check Level message came on. I stopped the car immediately and checked the coolant recovery tank and fluid was full. Did a lot of reading and unplugged the washer level (which was full as well) sensor and Display Defective came on. Cleaned both the washer sensor contacts and the plug contacts with electric cleaner and put everything back. So far no message for a few weeks now.

My conclusion (so far) is that my coolant level sensor is fine (so is the washer fluid level sensor) but there was a little corrosion on the washer level sensor contacts and that trigged the (wrong) display message.

 

I had the display defective message come on earlier this week. Both symbols appeared, washer fluid and coolant. I started solving the problem by cleaning the windshield washer sensor contacts and the message remained. Next step, replacing the ww sensor, it worked, message gone.

This thread was very helpful. Thank you loubapache and all who added their comments to this thread

 

Congrats. It is a puzzle, isn't it?

It is unnecessarily and overly complicated, IMHO.

 

For my 1997 E320, I just checked EPC and when I click on the coolant level sensor it says not applicable to this vehicle. Does my car have one of these sensors or not?

 

Yes, your car does, gmercoleza. I have the same 1997 E320. As a matter of fact, most Mercedes passenger cars after 1996 have this system.

 

Thanks Lou, so where is it then? I don't see anything plugged into my coolant reservoir - is it maybe plugged into the bottom? I can't see anything...

On a side note, I pulled my washer fluid sensor to check it out. The float moves freely, and I was able to bench test it. Upside down (simulating float all the way up) the resistance is about 180 ohms. But when I installed back in the car (with reservoir about 1/2 full) there was very little resistance. I don't recall the reading, but it was more like 20 ohms rather than 180. Does it sound like this sensor is fine?

I'm tempted to just buy both sensors new, but it doesn't make sense to do so without establishing that they are in fact defective.

 

The coolant sensor is on the bottom of the recovery tank.

For the washer sensor. Fill the reservoir full and measure again. It should be around 170 Ohms (plus and minus a few). If it measures considerably below that, try to tap it to see if it goes up. Chances are that the floater mechanism got stuck.

 

So in theory, can I just go to Radio Shack and get the equivalent of 170 ohms of resistors and "eliminate" the washer level sensor? That's not a function I need in the immediate future, and I'd like to rule it out before spending $50 (price at the dealer I just called).

 

Yes, you can, gmercoleza, if it is the washer fluid sensor problem. We do not have much posting about this in the W210 forum. Other forums have more about this when people use a new resistor. The 170 Ohm is th factory spec and anything that is a little more or less will also work.

 

OK thanks, the thinking here is that I will swap in resistors. IF that doesn't work, then I know the coolant level sensor is the culprit. Do you know the resistance of the coolant level sensor? Because I just might "eliminate" it as well temporarily. I am not getting readings from either of these sensors anyway while the "display defective" error message is in effect.

 

These are the resistance values for the inside the sensor. When a sensor goes bad, the resistor is shorted so the output is 0 Ohm. Or the sensor is open so the resistance is infinite.

When you see the display defective msg, it means the circuit is open. So it could be one of the two sensors (more likely) or the circuit itself.

Radio Shack sells many resistors in a 5 per package for about $1. When I did my own trouble shooting, I did buy some but my problem ended up with the most uncommon cause.

 

I got resistors from Radio Shack and simulated BOTH the coolant sensor (110 ohm) and washer sensor (170 ohm) simultaneously and still got display defective. I did double-check the resistor combinations with my meter and got 106 and 168 respectively.

What is the next step?

 

So you have taken the plugs off both sensors and put the resistors into the plugs (female ends) at the same time and still got the same msg?

If that is the case, then somewhere the circuit is open. One of the two wires in the plug for the washer fluid sensor (S42) should be connected to ground and the other wire is connected to one of the two wires at the coolant sensor (S41) plug.

Other than these, the rest go to the instrument cluster and is harder to check.

 

Windshield washer fluid sensor is very easy to locate and test. I tested mine and it is around 174 ohms.

However, the coolant level sensor is not that easy to find. Is it the one at the front bottom of the expansion "tank/bottle" near the fender? Disconnect it and test as WW sensor?

The problem that I have is "coolant low" message on a 1999 E320.

 

Windshield washer fluid sensor is very easy to locate and test. I tested mine and it is around 174 ohms.

However, the coolant level sensor is not that easy to find. Is it the one at the front bottom of the expansion "tank/bottle" near the fender? Disconnect it and test as WW sensor?

Yes, on the bottom of the recovery tank. You do not need to disconnect any coolant hoses. Just remove the single nut that holds the recovery tank and then carefully move the recovery tank so you can disconnect the plug.

 

Okay, thanks. It really helps to do things with guided instructions.

My problem is a "coolant low" on a 1999 E320. I will check the coolant level first and test the two sensors.

Hopefully, it is as simple as a "defective cap", "defective sensor" type problem.

 

loubapache and others,

Thanks for your help.

Had my first DISPLAY DEFECTIVE with no washer or rad pix, just the message, about two months ago. Went away at next engine start.

Same came back about a week later, cleaned washer level sensor, didn't look good at all. Also cleaned radiator overflow tank level sensor, looked pretty clean though. Checked resistance of washer level transmitter, that was bang on at 171 ohms.

Problem hasn't come back for over a month now, so I guess it's fixed.

Thanks guys for your posts, would suck to have to troubleshoot this without the internet and forums like this one.

Cheers

 

Don't replace anything untill you have cleaned washer and coolant level sensor connector. Also do the resistance check as posted. I cleaned both on mine, washer connector didn't look good at all. Message hasn't been back for over a year now.

Cheers

 

Who can tell me what is mean DISPLAY DEFECTIVE with this image... hey, why put imagine is so dificul? i should put it somewhere in web first? i can't just insert from my pc?

OK look here http://mb1.lt/showthread.php?p=356217#post356217 by boozzy