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  #1  
Old 04-28-2001, 09:45 PM
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Gilly... how can I test my vacume pump for the central locking system? For 300E, 1987. Sometimes it seems to have power to it at other times not. I have yet to hear the motor for the vacume operate. Sometimes I can hear the signal from a door or trunk going to the motor's control but that is only a very faint click. Other times the board or motor makes a faint sound...
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1993 190E 2.3
2000 Toyota 4x4 Tundra
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Old 04-28-2001, 10:14 PM
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Earl: Check out the power connector first, that's the 3 wire connector. Socket 1 is ground(the brown wire), Socket 2 is hot in run or start, thats a black with yellow stripe, power coming from fuse "A", Socket 3 is hot at all times (this is most suspect) red with white stripe coming from fuse "C". Make sure those 2 fuses are OK. If this all checks out, it's more than likely the pump itself is busticated. Either that or you have a triple failure of the microswitches.......Gilly
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Old 04-28-2001, 10:52 PM
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Thanks Gilly,
Thats a big help. I am currently working on the pump and have it on the bench. I removed the pump wires from the circuit board and put 12 volts directly to the pump and it works like a champ.

Now I'll check out the wires you mentioned and recheck the fuses.

Where are the microswitches located? On the circuit board inside the pump housing?
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1993 190E 2.3
2000 Toyota 4x4 Tundra
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Old 04-28-2001, 11:08 PM
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Earl, no, I should have mentioned that. What I mean are the microswitches in the 3 lock cylinders. I assumed (never a good thing to do) that it isn't working any any lock (both front doors, nor the trunk lock cylinder). If you're not sure, I'd plug it back in and check out what works and what doesn't. If the system is inop at only 1 lock, then I "take back" previous comments and suggest instead asking a knowledgeable, competent, helpful MB tech if he can fill ya in on checking out a switch instead of playing with the pump
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Old 04-29-2001, 02:16 AM
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Ok Gilly,

I now follow you regarding the switches. They seem to work. They send 12 volts (at least the driver's side and trunk)to the blue wire of the three pronged plug at the pump housing. This occurs when I press the lock button at the drivers door or turn the trunk key.

In turn, the circuit board is activated and the points of one of the small copper coils on the board begins to vibrate. But the motor does not run. I believe the points should only make contact and not vibrate. There is current at the two prong connector that powers the board and pump. The vibration stops after about 30 seconds.

I know the motor works because I had disconnected it from the circuit board and ran 12 volts to it.

It looks to me like something is wrong with the circuit board.

Anybody out there have an old vacume pump that I could have the circuit board out of?

One man's trash is another's treasure!

Smiles.

[Edited by ejsharp on 04-29-2001 at 01:28 AM]
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1993 190E 2.3
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Old 04-29-2001, 12:10 PM
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Earl: Did you test the 3 pin connector yet?

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Old 04-29-2001, 01:44 PM
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No, I did not test the connectors at the two front door and the trunk. I've been testing the motor and circuit board. I now have them operating directly off a 12 volt battery by putting current to the two pin connector of the circuit board, then connecting a common ground between the two and three pin connectors of the board, and then activating the board and motor by toutching one of the two remaining pins of the three pin connector with 12 volts.

When I do this the motor works.

Now to do the test of the three pin connectors in the doors and trunk.

I got side tracked because I had to repair the charger on my son's cell phone.

Off to do the tests now. Will update as soon as I know something.
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1993 190E 2.3
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Old 04-29-2001, 05:00 PM
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Gilly,

I tested the three pin connectors in the driver's and passenger's doors and the trunk.

However the wiring colors are a bit different... maybe because I have the security system where the lights flash and the horn beeps.

The wires at the locks are as you describe them... red with white stripe, brown ground but there is no black with any colored stripe. Instead each of the 3 connectors has a uniquely colored third wire. The driver's door is blue, the passenger's door is green and the trunk has a yellow third wire in the connector. Each of these unique colors: blue, green and yellow run to and make up the three pin connector at the pump housing. There is a second TWO wire connector at the pump housing. It contains the red with white stripe(hot always at the two pin connectorof housing, yet hot at the pump only when lock is activated) and the brown ground.

When I tested the three pin connector at the drivers door I found that the red and white is hot with 12 volts... same with the connector at the trunk. But the passenger door has only microvoltage... essentially dead.

I cannot seem to get voltage to any of the third wires (blue,green, yellow)... I tested with key on and off and lock up and down doors open and closed. I suspect these wires serve to activate the switch of sorts on the circuit board in order to operate the pump.

So I suspect something bad in the passenger door and possibly a bad circuit board at the pump. (I'm assuming the microswitch you mentioned is somewhere in the door)

Edited update.

I took a 12 volt battery out and hooked it to the pump with the vacume lines attached and when I activate the pump all the locks in the car including the gas tank do fuction.. they go from the unlocked to the locked position. That means the pump and vacume lines are OK.

So I figure the board too may be OK but something is wrong in the doors (as you suggest). Any idea what I might look for and can I repair or clean up the door switches or whatever else is in there? Fuses are OK.

[Edited by ejsharp on 04-29-2001 at 07:00 PM]
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1993 190E 2.3
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Old 04-29-2001, 08:35 PM
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On the 2 pin connector, the red/white stripe does have batt voltage, and you tested that the brown wire is providing a good ground?........Gilly
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  #10  
Old 04-29-2001, 11:12 PM
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Yes on the two pin the red/white has battery voltage and the ground is good. Don't misunderstand me.... the red/white is not supposed to be hot at the pump... the R/W wire ends at the two pin connector and feeds constant current to the circuit board. In turn the three pin is also connected to the circuit board and it's function is to signal or switch current from the R/W wire to the pump motor. Signals come from either of the two front doors or the trunk when the lock is mechanically activated. Thus the blue, green and yellow wires, one of each coming from the two doors and trunk.

If the blue is activated at the driver's door then it signals the circuit board to send current from the R/W to the pump motor. Same with the green and the yellow wire. Each activates the current from the R/W wire. Green coming from the passenger door and yellow from the trunk.

The problem seems to be that the circuit board is not getting the signals from the doors or trunk. I am certain that this is the case with the passenger door lock. Other reasons why the motor does not activate may lie in the circuit board. Maybe the voltage from the locks is too low to activate the electromagnetic points of the circuit board.

Is it possible to clean up the contacts in the two front doors?
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1993 190E 2.3
2000 Toyota 4x4 Tundra
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Old 04-30-2001, 08:26 AM
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Earl: I just had to make sure that the power and ground were there for the pump to run off of. The earlier posts didn't specifically state this, just the fact that the pump will run with power and ground applied to the 2 pins. you could try messing with the microswitches, but again let me point out that you would have to have a triple failure of the microswitches for this condition to exist. Let me look at a better diagnostic manual at work today and I'll get back to you......Gilly
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Old 04-30-2001, 09:48 AM
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Ok Gilly. Now that I understand how the system works I will go back a do a more in-debth check of the R/W wire and the brown ground.
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1993 190E 2.3
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Old 04-30-2001, 11:39 PM
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Earl: Let me know how you're doing. We were in the typical Monday Chicken-with-it's-head-cut-off mode today, didn't get a chance to look up anything. This weekend I was looking through my 124 CD-ROM from MB, got some conflicting info. Those discs aren't everything their cracked up to be, not when you compare it to info in a MB shop. The connector I referred to as the 3 wire is actually a 3 socket connector, with the 2 wire going into it, as you've discovered. This actually powers the pump, the other connector is to trigger the pump, not run it. On the other circular connector, is there an intermediate connector that connects to the pump, then the other connector plugs into that? An intermediate connector would be for a anti-theft system. If you have it, disconnect it and plug the pigtail directly into the pump without the intermediate connector, to by-pass the anti-theft and see if the central locking works without the anti-theft......Gilly
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  #14  
Old 05-01-2001, 12:34 AM
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Yes... the blue ,green and yellow wires are the triggers coming from their respective locks.

On the 87 300E there are 2 three pin connectors and 1 two pin connector near the pump housing but only 1 three pin connector plugs into the housing along with a separate 2 pin connector (R/W and brown ground).

The third connector which is a three pin connector also with blue, green and yellow wires plugs into a white cable that disappears under the rug in two directions. I have no idea where it goes or comes from... It just lays next to the pump housing... and I don't know which of the two should plug into the pump because they are identical... with the exception that one of the two connectors has slightly heavier gauge wires.

Yes the car does have the anti theft system. I suspect that it is somehow incorporated into the three pin connector coming off the door or trunk lock.
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1993 190E 2.3
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Old 05-02-2001, 05:36 PM
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Gilly,

I want to try to catch you before the week end. Is it possible for you to copy the complete wiring diagram for the central locking system for an 87 300E?

I bought a new pump housing assembly (complete with circuit board and pump) .. but I still get zilch.. no response from the system when I lock either of the two front doors or trunk.

That means that the trigger signal is not being sent. So I need to trace the lines clear back to the fuse box, (relay if involved) and the warning light/beeper if appropriate. My info from Alldata says the car should have a warning signal in the dash someplace. But I get no warning of any kind...sound or light signal.

It is important for me to know if a relay is involved and if so, which one.

I'd like to work on it this week end if possible. You can e-mail a copy to me at ejsharp@erols.com or fax it to 301-292-1070.

Thanks.



[Edited by ejsharp on 05-02-2001 at 09:38 PM]
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