From your post, I assume that the convenience control unit is the one I call power window module. So, now I know what convenience control unit is.

You mentioned CAN twice and I forgot to ask, What is CAN?

 

controllers area network

it is a signal
much similar to your internet connection. they communicate through this system.

 

OK, here is my update, just in case you all need to know what have I done.
Sorry for being absent in a week. I had other things to do so I had to stop working on the car.

Last time, I looked underneath the fuse/ relay box. I found 1 red wire hanging loose and 1 small pink/yellow wire had been spliced and somebody had run a red wire (that goes to a blue relay in relay box) into that wire. The splice connection was badly corroded. I think the 1 hanging loose was supposed to be connected to the 1 that goes to the blue relay. So, not knowing any information, I fixed the wires. Then I tested the window(hoping that would fix it), it worked. That was one lucky fix, or it's probably an intermittent fix, we'll see.

I've got 3 relays in my relay box. One is green-fused, one is blue-fused, and another one is blue without fuse. Do you know what are they for?

So, forgetting about the lucky fix window, I'm moving to the interior lighting and radio problems. Sleepwalker, would you mind posting me the wiring diagrams? I don't believe mine.

Info on the interior lighting:
If I put a good fuse in, the interior lights, instrument illumination & license plate lights are on, but not any exterior lights. I checked the fuse terminal (with the fuse out) and I got both power and ground on the 2 contacts all the time.

I can't get the headlights to turn on. I can only operate 1 click (parking light) on the light switch. That looks like a bad switch to me. Any objection? Is the interior light circuit probably grounded on the switch because the switch is burnt or something? I took a look at the switch and I was afraid to disconnect it from the harness, since it's very easy to switch the wires around and have them shorted to ground.

The clock on instrument cluster looks very dim. It is barely visible

Info on radio
This car has got an old alpine radio cassette player.
Last time I traced the radio wire and i found a red/purple wire as the constant 12V .
I checked the voltage, it only had about 0.3 volt. After that, I couldn't check further, I didn't know where the wire was supposed to go.


Thanks in advance.

Bob

 

the two relay could be for windshield wiper, and the other one for the washer. you can pull them out and test.

check the bulb on instrument cluster illumination, especially the one behind the clock.

about the wiring diagram, i got many versions and i am afraid i might send the wrong one. i will study it first.

 

Thanks sleepwalker.
Hopefully I don't really have to pull the whole instrument panel out. Since taking the whole assy out may mean taking off the steering wheel & also the airbag unit.

I'll post any additional info.

Thanks.

 

i didn't know that you need to remove the steering wheel to pull out the instrument cluster. i have no experience on that.

you just do what you decide to avoid aggravation.

 

Hi all & sleepwalker,

Looks like I have to take the steering wheel off to get the instrument cluster off. The space is rather tight.
But thanks to my laziness, I rather played around with the switch than tried to take the instrument cluster out. When playing around with the switch, I was able to turn the lights off at a certain position. So, I decided to replace the light switch. It works great now.

When replacing the old switch with the new one, I compared both of the switch, and shook them. The old one had a noise like there were sand/ small rocks inside. The new one didn't make any noise.
I opened it and particles dropped out. Looks like I will never be able to put the old switch back together.

The radio was also miraculously fixed. Last time it didn't have the constant 12V. But today, there was 12V on the red/violet wire. So I hooked the radio up and turned it on.
It worked. I can only hope it is a permanent fix.

Well, that's my update.
My special appreciation to sleepwalker for being nice and very helpful.
Sleepwalker has been very helpful to everybody who shares problems.

Thanks!

[IMG]local://upfiles/3126/75154E866B614CFEB263191E52A77D67.jpg[/IMG]

[IMG]local://upfiles/3126/F46359EC217E4DA08C9B8B4033514FAB.jpg[/IMG]

[IMG]local://upfiles/3126/56D1938037204B0CB02D6EDCC0B61DBF.jpg[/IMG]

 

Looks like the switch is a common problem.
My 95 C180 has a bad light switch too.
I'm gonna have to replace it soon.
Also the hazard switch went bad too.

Why does Mercedes design poor switches? Anyone knows?

My other friend's 95 C180 had an a/c blower switch problem.

Japanese cars rarely have switch problems, well at least not as many as I've found in Mercedes. 3 cars in a row, in a short time, with switch problems.

[IMG]local://upfiles/3126/683F1759DC98434BB28BDBE01E6F2AA1.jpg[/IMG]

 

on older model they use poor materials in switches and they were supplied with direct voltage, but lately less load and no problem.

you have done a great job. i always know you have the capability of doing it.

have a nice day.

 

I suggest you to get a Factory Mercedes Manual.

It has all service and maintenance instructions, step by step.

A great help, hope this will help you.

Here's the link:
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMESE%3AIT