Vacuum pump location in C280
 

Ok, I know this topic is one that is somewhat annoying, but I'm really trying to get this information so I can complete this mod myself. I've read EVERY post on how to add remote door locks to the Mercedes’ vacuum system and I have even installed this on my old 190e.

Now however, I have a C280 and I want to accomplish the same task. However, on this model the vacuum pump is in the trunk and I don't know which wires to cut to install my keyless unit. I've read the excellent write up for the W124's and could do it without further assistance, however, as mentioned my C280 is a bit different.

Could someone PLEASE assist me in locating the correct wiring information? Even if you have a wiring chart or know how I can obtain one this would be a great help!

I've always found this site to be helpful and very informative. Please guys, don't let me down!!

Thanks,
Corey

In regards to your SUBJECT (albeit contradictory post), vacuum pump is in the trunk on the right side behind the cover. Seems as though you know this though!

Well per your request, I just tried to open my CDRom, 202 Systems Information, but the damn thing is scratched and will not read! I am having my mom bring home a Data Cd from the office, and I will try and copy it on the other computer (less sensitive reader) and then see if I can read it from there (that computer doesn't have a supported driver to read the cd though?).
I can't even be sure if it has the wiring diagram, as it's not a Tech manual/CD whatever, but it might be a start.
Also keep in mind that the W202 tech CD should be coming out in September, per Mercedes-Benz. That will be an IMMEDIATE purchase! For me, anyway.

Ok, that's all the help I can give for now. But since you are doing this yourself, I have a question. My aftermarket alarm/remote today began acting up. When I click the lock button, the alarms chirp, but the door locks do not activate. If I open the door, the alarm will set off as usual. So the alarm is activating but the door locks are not. Upon further investigation, I noticed that the switch on the console is fully functional (unlocks and locks doors properly). I also sat in the car, activated the alarm and then unactivated it. I was able to hear the vacuum pump turn on when I would disactivate, or UNLOCK (via remote) the car. So I know that the alarm is working normally to unlocking the doors, but there is no pump activation when LOCKING/activating the alarm. My question:
Are there 2 wires to the vacuum pump, one for unlocking, and one for locking? If so, then I am assuming the lock wire (wherever the alarm is put in-line with it) is acting up. Today it has worked and not worked, then worked, and now not worked. Sorry to distract from your original request, but I was just hoping you might be able to help! Thanks again, and I'll keep you posted. GOOD LUCK!! :D

The pump is on the passenger's side of the inner trunk panel. You will have to remove the inner fender lining to find it.

I ususally put the controller in the area under the black panel in the forward center part of the floor of the trunk. You will have to remove three plastic nuts to access it. You will find plenty of room there. I don't remember the colors, but you will find them on the pump.

David,

Yes there is a lock and unlock wire coming from the brain of your alarm. The wires are spliced into the vacuum pump - the wire that is cut is the one leading from switch (door lock) to pump. If one function is not working (lock or unlock) then you may have faulty wiring at that wire only. You may want to find the pump and see which two wires has been spliced into. If you get the right wire, when you disconnect one, either the lock or unlock will not work with the remote.

When you find it, please let me know the color of the wire and in which plug it's located on. Thanks for trying to find a diagram for me, you're the best! Let me know how you make out.

Benzmac,

Thanks for your post also. I've a question, does the pump in the trunk have the same wire colors / harness shapes as the W124 write up for the kit you guys used to sell? If so, then perhaps once I can locate the pump I can just follow the directions from there. All I need is the wire location / color to make the following connections:

A) Constant Power
B) Ground
C) Wire from switch to pump
D) Switched power (optional)

Actually, on second thought, the battery is in the trunk already so A and B I already can find. So I guess I just need the info for C. Hey, I'm getting closer....


Thanks!:)
Corey

Ok, I located the vacuum pump. Here is a break down of the wires that are attached to it:

There are three wiring plugs going to the pump. Two of the plugs are grouped together (total of 4 wires) the third has a total of 8 wires.

1: Two Wires
Blue / Black
Blue / Yellow

2: Two Wires
Red / White - Blue stripes
Grey / Red

3: Eight Wires
Brown
Brown / Yellow
Blue
Black
Red / Grey
Red / Grey
White / Green
Blue / Brown

SO here is the million dollar question. Which wire is the one that goes to the switch and unlocks / locks the doors? I'm thinking it must be on one of the two small plugs.


Thanks,
Corey

Ok, here are some pictures of the vacuum pump.

http://www.a-p-group.com/cklasse/VacuumPump.JPG
(I am still wondering why that blue wire is cut (the other end is grounded....)

http://www.a-p-group.com/cklasse/VacuumPump2.JPG

http://www.a-p-group.com/cklasse/VacuumPumpWires.JPG
Hopefully you can see all of the wire colors here.

And I still cannot figure it out (for you Corey), which wire controls the lock/unlock?! Hopefully some one else will know!

David,

Very interesting. According to my understanding of how alarms & keyless entry work in MB's, when splicing into the vacuum pump you do the following:

:http://www.geocities.com/brg_miata/vacuumlocks.gif

When using relays (our vacuum system requires two relays), the two green wires (87a + 30) must separate the lock/ unlock wire. This means two cuts. In your photo, I only see one. Perhaps this is your problem. If that wire is not connected to something how will it be able to function??

By the way, what is the exact color of the wire?


Interesting......:confused

Corey,
The blue wire is the only wire that is cut, and it has always been like this. The lock problem hasn't occurred in the past few days though... hopefully it was a temporary glitch.
But yes, the wire is blue, and it's cut, why? And the other end is grounded. I still don't understand how this works?

Dude, this is really strange. I think we need help from the experts......

Corey,
Your link/pic doesn't work? Will you put it in again? Yeah, I hope the pros can help us out!!

Ok, it should be back.

NOPE! :confused: :o :eek: :eek: :confused: :o

Corey, try this:
http://www.peachparts.com/shopforum/mercedes-benz-performance-paddock/22396-remote-start.html

Relay Diagram for vacuum locks
 

Hooked up the keyless entry today. I tested the various wires on the larger connector and I found that the White / Green wire is connected to the dash door lock / unlock switch. I spliced in my relays here. The doors lock & unlock fine, however, when I lock the doors via the remote, the factory alarm is not engaged. Similarly, when I lock a door with the key (factory alarm on) I cannot unlock them with the remote. I'd assume that I should use a wire that is connected to the door.
I tested the blue wire and found that when cut, the doors will lock with the key but not unlock. When my keyless entry relays are connected the remote will only unlock the doors and will not deactivate the factory alarm.

Man, this project has me scratching my head. I also tested the blue / brown wire. When cut, there is no affect on locking / unlocking with keys or dash switch. The only other wires I’ve not tried are the black and the orange / gray wires.

A summary:

3: Eight Wires
Brown -> ground
Brown / Yellow -> ground (?)
Blue -> driver’s door unlock
Black -> (?)
Red / Gray -> power
Orange / gray ->(?)
White / Green -> dash switch
Blue / Brown -> no affect

Any suggestions?