g.coleman

I am new to MB World and have just purchased a '95 E320 Cab with 77K miles. A nice car but I have 2 questions--behind the fuse block I hear what sounds like a relay clicking when the car is not running--any ideas?
Also--when the car is cold I think the power steering pump is noisy--took off the cap and the fluid is not to the top of the reservoir and I don't see a dip stick to advise the correct level. Should the fluid be right to the very top?
Thanks Gary

Floobydust

The clicking is probably the convenience relay/controller which is located in the relay box behind the fuse box. You need to remove 4 Phillips screws to remove the cover to this box. There are several relays in there that control various functions. You can probably "feel" them to see which one is clicking.

Do yourself a favor - when you have the cover off, you will see that there are several blade style fuses which are part of the various relays. Proactively check all of them to see if they are blown. Two of these relays/fuses control the auxiliary cooling fan operation. Because the M104 engine has a mechanical cooling fan as well as the electric fans, you may not notice a blown fuse here until the engine overheats.

Not sure about PS pump/level.

- FD

g.coleman

I will take the cover off and see if I can tell what relay is causing the noise. I suppose the relay should be replaced when identified? Do you know which fuse controls the seat belt extender? Driver's side is not working just making a grinding noise when I first start the car--I guess the teeth are stripped. I don't want to repare this just disable it.
Gary

Floobydust

g -

That depends on which relay. If it's the convenience relay, replacing the relay would be a good first step as these are known to have issues. The convenience relay is also the only one that can "self activate", e.g., could making a clicking sound in the absence of an external circuit fault.

If it is one of the other relays, there is likely a secondary issue that is causing the clicking of the relay. The path of investigation will depend on which relay is singing.

There is no dedicated fuse for the seat belt extender, so you can't disable it that way. What you need to do is disconnect the portion of the wiring harness that drives that extender. The seat best controller is located under the rear seat on the passenger side. If I remember correctly, the controller has three connectors attached to it. One for each extender actuator and one that is the interface to other car inputs/power. The two for the extenders will look almost identical. You should be able to see which one leads up to the passenger side extender, so disconnect the other one and you should be all set.

- FD

FYI, don't confuse the seat belt controller with the top controller which also has three connectors. The top controller is the first one you will likely see with part No. 124 820 45 25. It will also have a firmware version listed on it.

g.coleman

Thanks__I probbly can't get to it unti the weekend and I'll be careful on the controllers..G

Floobydust

g -

Here is a picture of the controller you will be looking for. I guess my memory is not as good as it used to be as there are only two connectors to the controller. You will want to pull the bottom one out by pushing the slide on the left toward the right. I, on the other hand, will want to pull my head out of my a$$.

This will, unfortunately, disable both seat belt presenters as the power and drive motor control in part of one connector, but it will stop the grinding.

- FD

g.coleman

FD--thanks. A picture is worth a thousand words and this gives me a real good idea of what I'm going to need to do.
G

g.coleman

Hi FD--just finished discounting the controller and that anoing grinding noise is gone. You picture was a big help as I new exactly which box to deal with. Do you know if discounting this will affect the operation of any other things. Next job is figuring out which relay is clicking.
Thanks G

Floobydust

G -

Glad you were able to find it. Disconnecting the controller this way should have no effect on any other system in the car.

Just out of curiosity, when you say relay clicking with the car not running, does "not running" mean key out of the ignition or key turned, but the engine not started? Also, how fast does the relay click - once a second, once every ten seconds, etc?

- FD

g.coleman

FD --with the key in or out of the ignition the clicking is about every 5 seconds. I thought at first it might be the clock but it definitely sounds like a relay just behind the main fuse panel under the hood on the drivers side. Just back from a drive and it sure was nice to get in the car and start it without that annoying grinding sound. G

Floobydust

G -

When your in the car, start the the engine, then turn it off and remove the key. Do not open the doors. Do the power windows still work? If so, for how long (> 1 min)? Do they shut off in time to the relay clicking? Clues to diagnose the convenience relay.

- FD

Floobydust

G -

Quick follow up - I timed the intermittent wiper relay (which also located behind the fuse box) and the period is just about 5 seconds. I would say that's your relay problem, except that the wiper circuit is powered only when the key in on. Pull the wiper fuse and see if the clicking goes away. Perhaps the circuit is getting power when it should not be (DPO did some "electrical work").

- FD

g.coleman

FD--thanks for the tips. I checked the windows and they continue to work with the key out (the top is down and I don't know if that would make any difference?)
As I look at the fuse box from the front of the car --the 2nd row of fuses which I think is Row C?? --I pushed the fuse clip up so as to remove the first fuse on the left side and the clicking stopped. If I have identified the row correctly the first fuse on the left side closest to the engine is #9 which according to the fuse box cover sheet is for "diagnostic term 6, hazard warning system, clock, front roof light, vanity mirror light, relay comfort circuitry term6" (the relay clicked a couple of times rapidly and then quit.
When I lifted the clip on the next fuse (#10--again If I have identified the correct row according to the sheet) the clicking promptly stopped.
I don't know if the previous owner did electrics or not but one other thing is that the cover on the passenger vanity mirror had broke off and I velcroed the cover to the mirror--the small hinges which would turn the light on are broke---if Fuse #9 controls this could this be the issue? G

g.coleman

FD--also tried pushing up the clip on what I think is the wiper fuse and the clicking continued. G

Jim's500E

The p/s res. should have a white(ish) level indicator inside it. There is also a filter in there that can be changed for less than $10.

Steering racks can go bad tho...especially with a car this old.

Floobydust

G -

It seems like convenience circuit is working okay, but the wiper circuit is being back-fed from somewhere. It could be a problem with the fuse fuse box itself, but more likely, it is somewhere else. Fuse 2 & 3 are involved with the wiper system/relay. Fuse 9 is the jack-of-all-trades fuse for switched power and fuse 7 is the jack-of-all-trades fuse for constant power.

Some more questions . . .

On the window test I described, if you open the doors, do the windows then stop working?
Do the wipers run with the key off (they shouldn't).
Does the clicking stop/change when you turn the headlights on/off?
Does you car have an aftermarket stereo? I have seen an incompetent installer bridge the switched and constant power circuits. I have also seen an electronic failure bridge these two (there is typically a diode that supplies memory power from the switched power when the stereo is on - if that diode fails, it will bridge the two).

- FD

g.coleman

FD--windows still work with door open and key out.
Wipers do not work with key out.
Clicking still there with headlights on or off
Yes--car has an aftermarket stereo--I also note that there appears to be a cable of some description wired into the positive side of the battery post--almost looks like an antenna lead (round and sheathed) but I have not followed it to see where it goes--I will need to do this in the daylight

I also looked at the fuse box with a flashlight this time--the first fuse I described above is actually C and the 2nd one that I described is actually #9. Booth of these will stop the clicking.
G

g.coleman

Reply to Jim--I don't see a dip stick on the bottom of the cap but the fluid level is about 1 1/2" from the top. I will try to have the filter changed. The noise only happens immediately after start up and disappears when the car starts to warm up in about 1 minute or so.

Floobydust

G -

The windows should stop working once you open the driver's door. Fuse C and 9 are both hot at all times circuits. Both can feed back to fuse 2 (the wiper relay) via either the convenience relay and controller circuit or via the stereo (stereo memory or power antenna).

With the key off, does the clicking stop when you turn the wiper switch to low speed or high speed?

If you remove fuse 2 only, does the clicking stop?

Do you have access to a volt meter or 12 volt test light? If not, Radio Shack catalog no. 276-270 12 volt LED ($2.49) can be used as a test lamp. Check for voltage on fuse 2 with the key out, e.g., one lead to metal chassis ground, one to either fuse clip (observe polarity per the info on the LED package). If you have power on fuse 2 with the key out, remove fuse 2 and check which fuse clip is hot.

- FD

allenjdmb

but you can fix the awful noise on the seatbelt extender. The gears usually lose a tooth or two, and won't co-operate. There are a couple of Benz geeks who acutally make them and you can replace them. Did it on my R side on my 94 E320C. So nice for them to work!

g.coleman

FD. Clicking does not stop when wiper is turned to low or high with the key out. Removing fuse#2 does not stop clicking. I will get a tester this weekend and see if the terminal is hot with the fuse out. Clicking only stops with either C or #9 removed
Thanks for the help.
G