1998 E320 with weird electrical problems…
 

Hi all, I have a 1998 E320 with weird electrical problems… I noticed the sun roof problem first. One day it seemed like the motor was going out when I tried to open it. It would go and cut as if you were trying to open it by touching two bare wires together. Then later I noticed that I had to point the key fob to the door handle to lock and unlock the car. Then the dome lights in the front won’t turn on at all and the garage door opener doesn’t work either. I have checked all the fuses and they are all fine; any relays to check?

Thanks!

Fuse 4 in the F4 panel under the rear seat powers the roof module.

When you're checking that fuse, ensure that there is no water under the rear seat.

Thanks! I have checked all the fuses... I'm thinking it could be a relay or a computer that controls the sunroof, dome lights, garage door opener and the receiver for the lock unlock function on the key fob.

The relay or module IS the roof module. The sunroof switch is PART of it.
N70

Thanks Steve, does that relay also provide power to the other things that are not working? Or is it just for the sunroof?

MB along with most other manufacturers use a network of zone controllers. Small computers that talk on the network. They interpret and communicate sensor data from sensors close by to other controllers farther away and the drive elements that are also in their zone. An example here would be that the roof module has the inside air temp sensor. It interpretes the temp and sends it over the network to the A/C controller (it does this digitally rather than actually separate wires). Another sensor up there is the radio sensor for the remote control (I think radio rather than infra red).

It of course has the sunroof controls and also has the rain sensor for the intermittant wiper I think.

Unfortunately, after checking the fuse the next step is to communicate with the module and see if it is upset about something.

got it! thanks Steve... do you know if there any way I can check the N70 or do I just have to purchase one?

Can you talk to it?

Sure I can try! I talk to my car all the time. What should I ask it?

Ask it how it is doing.

But of course the most important issue is whether it answers. And it has to be N70 that answers.

MB had several updated parts for the sunroof controller /switch,all poor quality,it is one hard to find part, used,because the new ones are outrageous,I belive 500$,common part to brake and sunroof will be stuck,I belive all models up to 2001 are affected,dealer allways keeps a good stock on those parts,unless you have a unusual interior color to match...

Alright Steve, I went looking for the famous N70 but it was no where to be found in there. I think it ran away! That explains the problem… :D I took a few pictures for you to see. I also replaced the fuse #4 in the fuse box underneath the back seat. Also everything on fuse box photo A and B that shows #4 does not function. What component does that fuse power?

I hope thats not my problem 92...
Personally I think it’s a relay or a component that controls multiple things. Or like Steve said the car does have a can bus system so a component may be shutting others down, down the line.

Upper left 208 820 19 01 repl by 208 820 40 01.

So is that what has caused my headache? What’s the different between the 2… is the first one discontinued?

Thanks for all your help:D

Hold on now. I never said that was your problem, it don't work like thatfor anyone that actually repairs cars. That is the module to talk to, it just happens to have something in common with your issues so that is where to begin testing. As I said before the first thing to do is to talk to it and see what it has to say.

Got it! So how do I talk to it to see if it's functioning properly? I took it out and everything on the circuit board looks good. How do I know if it's getting power or not?

You take the diagnostic computer and go to the EIS controller. There under actual values you will see the modules coded to the CAN B (interior CAN). You will then look at the inventory of modules reporting. This will tell you if the module is at home. If it is then you go to the Body section and pick out the OCM and communicate with it. If communications takes place you will have the oportunity to check for fault codes, actual values, and adaptations.

If it tells you every thing is OK then you have to get your wiring diagram and evaluate each circuit for what you expect from it.

If it don't talk then you need to verify that it is powered and grounded and that the CAN circuit is available. That is a little more complicated.

For more about that you can get a good description here:

http://www.mercedestechstore.com/pdfs/507%20Systems%20I/507%20HO%20CAN%20B%20(ICC)%2010-28-02.pdf

Great info Steve thanks!
Now where can I get an adapter to connect my computer to the car and where do I (if I can) get the utility to run the diagnostic?

Thanks again!