How do I reset the computers of a W140 - PeachParts Mercedes-Benz Forum

Vee12 · #1 10-25-2004, 02:23 PM

I have several problems showing in my cluster of my W140 , battery has been empty for a while and now driving it again , all kinds of lights go on in my cluster and gauges are not working correct. Who can help !!

Gilly · #2 10-25-2004, 05:37 PM

What year is it, and can you elaborate on what warning lights are coming on, and what are the gauges doing incorrectly? All I can find out about your car is that it's a 600SEL "Brabas"

Gilly

Vee12 · #3 10-30-2004, 04:15 PM

Hi and thanks for your reply .
Thge car is a 1992 imported by us from Germany.
The problem accord when the car had been sitting in storage with an empty battery, I have checked the battery and replaced by a new one and the problems started.
The new battery is charging 13.65 Volts with idling engine. but as soon as you turn it of the battery is using power to an unknown source.
It drains in 2 days completely to dead.
The cluster does not work properly also anymore ,
gauges of
Econometer
Speed
temperture
and cruise control ( maybe because the speedometer is not working )

Please let me know if you have any ideas where to look

THX Again
Ben

Gilly · #4 10-30-2004, 04:32 PM

Ben
Seems like a few different issues going on.
To determine the problem with the battery going dead ("flat" as YOU call it

), you need to have a current consumption test done. On this car, there normally is quite a large drain when the car is shut off. It DOES make a difference on this car if the KEY is left in the ignition, you should remove the key when the car is parked in a secure spot such as your garage, when the normal inclination may be to leave the key in the ignition. Remove it and put it on the dash or center console for example. On this car it would not be unusual for the drain (even with the key removed) to be as high as 40 or 50 ma (milliamps, there are 1000 ma to an amp). So, you need to find out if it is alot higher than this what the problem might be, such as a trunk light remaining on for example. The usual way of determining current consumption while at rest id to remove the negative terminal of the battery and putting an ammeter in line between the terminal and the negative cable. You might want to have someone experienced in Mercedes to do this, it would be easy to ruin the ammeter (or worse!) if you don't know the proper order of doing this(for example if the ammeter is hooked up and you open the door and all the interior lights come on you can blow the fuse in the ammeter, a mechanic would know this). Also it may take a bit of time before the car is fully "powered down" so you can see the "real number" of the draw. So that's one issue.
The other issue I think I can help you with, in regargs to the cluster not all working correctly after battery replacement. OK, under the hood area, on the right side (passengers side) back towards the firewall there is a "black box" (control module box it's called), and you need to remove the lid to get in to that. THEN you'll see one module in there that has a clear plastic lid, there are fuses under this small lid. I am betting one of these fuses are blown. This module with the small lid is called the Base Module, or "BM" for short. It protects various modules in the car from voltage spikes and reverse polarities, etc. Don't worry about the fact that not all the fuse ports have fuses in them, just check the ones that ARE there and replace any blown ones, make sure you put them all back in the original spots.

Gilly

Gilly · #5 10-30-2004, 04:41 PM

PS, the car certainly should last more than a few days without the battery going dead, so I do believe there is something left on or some other problem here. It would not be all that unusual for the battery to be dead after a month or so of non-use, so do expect that. Many owners of "garage queen" cars like this will choose to either install a battery "tender" or also called a trickle charger, to keep the battery "full" when just sitting, or may choose to disconnect the negative terminal when parked or install a battery cut-off switch to make the battery disconnection process easier. This method does has it's complications in that some of the electrical components will need some attention after disconnecting the battery, such as the clock needs to be reset, there is a radio code that needs to be entered to have "tunes" again, the windows need to be "relearned" for the auto up/down to work again, and on your 12-holer there maybe even more things than this that would need attention, so for that reason I usually recommend the battery charger route. MB has a really "slick" one which leaves what looks like a cigarette lighter socket in the trim in the trunk, and the carger has what looks like a cigarette lighter accessory plug whick plugs into this socket, and the charger itself plugs into you garage electrical outlet. I believe you can find generic versions of this setup, doesn't have to be from MB, probably just a Schumacher charger anyways.
Hope this all helps you, let me know if you need more info and also when you're going to let me borrow the V12 :p .

Gilly

Vee12 · #6 10-30-2004, 07:57 PM

Hi Gilly,

I have worked on the car today and made a lightbulp with two wires soldered to it so long that it could make it to the front of the car .
One wire connected to the battery ground and the other to the ground wire.
The light burned and this way I did not have to go back and forth to see the Voltmeter or bulb go on or off when I tried to determine the section of the power loss by pulling the fuses.
I have found out that the micro switch of the roof makeup mirror at the back seat area was burned and the light was constantly on ( could not see it because it was folded into the roof. PROBLEM 1 SOLVED THX !!
Problem 2
I have checked the fuses in the black box and F1 was burned out , I replaced it but there was no differance , Still most of the instuments are not working as dicriped , also is that I noticed the dual Fan in front of the radiator does not kick in and the fuel meter is still reading the amount of fuel from before I parked it ( noticed because I took the car for a ride and filled the tank up. Fuel Meter did not responce on more fuel.
It must be something thats controling or fusing this entire section ??
Let me know

I really appriciate your help !!

THX Ben

Vee12 · #7 10-30-2004, 08:05 PM

The ride will be on Me your more than welkom !!

Ben

Gilly · #8 10-30-2004, 09:44 PM

Because you said "Fuse F1", it makes me think you are in the fusebox itself (by the brake master cylinder) rather than in this control module box. Can you confirm you are in the box which contains only control modules, (on the PASSENGER side of the car) and not simply in the fusebox?
Gilly

Vee12 · #9 11-06-2004, 04:03 AM

Hi Gilly, sorry I was away for a couple of days, The fuse was in the passenger side computer box and on the plastic cover the fuses are listed from F1 to F5 ( very hard to see on that small cover)
The problem is still there and do you know witch computer controls these functions ? I drove yesterday a couple of miles and suddenly the speedometer started working and the cruise control ?? but today there is no sign of life again. Let me know

THX Ben

Gilly · #10 11-06-2004, 04:34 AM

Lots of computers are powered by those fuses. Did you have blown fuses in the Base Module or not?
Gilly

Vee12 · #11 11-07-2004, 02:17 AM

The blown fuse was in the box on the passengerside where all the push in computers are located The Other 4 fuses in there were still OK checked them with multimeter.

Ben

Gilly · #12 11-07-2004, 08:06 AM

OK, so you replaced the fuse, and did everything start to work again, or just the speedometer and cruise control?
Can you give a list of the problems?
After the speedo and cruise stopped working (the second time) did you check the fuse in the BM again?
Is it possible that when the battery was replaced that initially it was installed backwards and the battery connections were attempted to be installed backwards, or is it possible that when the battery was dead that someone attempted to jumpstart the car and may have tried doing it incorrectly and reversed the polarity?
Gilly

JimF · #13 11-07-2004, 10:44 AM

Mercedes web page and look at some of the "MENUs", especially MENU#2. You should be able to read the stored codes (DTCs) and see what further may be wrong.

Toward the bottom of the page, follow the procedure to get the DTCs and let us know. The codes posted for my car will be ok for yours too.

Vee12 · #14 11-08-2004, 01:47 AM

Hi Gilly and JimF, you have given me lots of home work again , i Will look into it and let you know , I can not recall the battery has been wrongly connected but I have had some boost in the past ( battery was dead lots of time but that problem has been found thanks to you. ( the make-up mirror in the rear headliner had a broken micro switch)
What would happen if there has been a reversed battery hookup ?

I will copy the scedule for the control test light and will build one this week.
Will get back to you shortly , THX good to know there is nice and proffessional help out there !!

Ben

Gilly · #15 11-08-2004, 08:13 AM

I still would like an accurate list of the problems before the fuse was replaced (which warning lights were coming on, which gauges didn't work, etc), then what was still not working after you replaced the blown fuse in the BM, and is it now back to how it was before the fuse was replaced, or is it now somewhat different than before?
The problem with an improper jumpstart or connecting the battery incorrectly is that it can damage electrical components. I am especially suspicious that your insrument clustrer may have been damaged, but it is too early to tell yet.
The fuse blowing in the BM may have saved some components for damage, but in the time it took for the fuse to blow, some damage may have occurred.
I have seen very expensive damage done to Mercedes (including a car very much like yours) by jumping improperly. It seems to depend on which components may have been operating when the charging was done, for example because the drivers door was opened, it ruined the overhead interior lamp, which contains a control module. On that particular car, it also had a blown fuse in the BM, but I replaced it and it fixed about 75% of the problems (warning lights and inoperative speedometer and other gauges).
Gilly

PS did you put the proper rated fuse back in to the BM? I think they are all red 10 amp fuses if memory serves.......

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