Good morning all,

Searched the archives for this topic and could not find any information on it.
I have a W126 with a 000 800 05 48 vacuum pump installed (well actually now it's on my bench). The pump electronic controller has stopped working a few day's ago. I have opened the box and have verified that the pump motor still works, but the electronics do not. Could a kind soul please send me the schematic for this or point me in the direction of where to get it?

Thanks very much for your help,

Adriano

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

You'll need to be more specific about what a "pump electronic controller" might be.............the typical W126 has a mechanical vacuum pump.........nothing more.

Hello Bryan,

Thanks for the reply. I have to respectfully disagree in that most of the post I read state that the W126 has an electric vacuum pump mounted in the truck area near the spare tire.

At any rate what ever the case is I have a 84 300SD which door lock system is operated via said electric vacuum pump. The pump assembly (once opened) has a control circuit which tells the vacuum motor when to shut off.
That circuit is what I'm asking the schematic for.

Hope this clarifies it,

Adriano

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

Yep........that vacuum pump..........not sure if anyone has a schematic for it. It doesn't fail often..........the best solution is to find a salvaged unit.

I have a box with eight of them for sale. Used/cheap, and my friend in So Cal has them with lots of other W126 parts we have just acquired and are just now sifting through..They were in the FIRST load. Got them free when I bought this car. Going back for more this weekend with a pickup truck to get the rest of them.










Let me know if you want one of them for a VERY reasonable price.


Best way is to compare parts numbers and pictures to be sure it's exactly what you need.

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)

Pardon me for speaking from total ignorance, but it would seem to me that for actuating the trunk lock, you would want the car to run the vacuum motor for a couple of minutes after the ignition is shut off, if the vacuum is low. This would be the series connection of the NO contact of a delay-on-off relay (McmasterCarr pn 6964K2-12VDC $61) with the contact of a low vacuum switch (Ford 81 granada vacuum switch connected to ignition computer).You would need a fused constant 12vDC wire to the relay power input, an ignition switch signal to the relay trigger, and connect the output of the vacuum switch to the vacuum motor hot. Of course, junk is much cheaper.

Hey guy's,

Jim B. love the wheels on the car PM me with what you suggest for price, might be it might be that I'll replace.

Indianajo
The board contains a vacuum device (really simple unlike the way we in the US think) that when sufficient vac or pos pressure is generated the contacts trigger a signal to an IC to shut the pump motor off, I'm sure that it also has a time limiter to shut off in case a preset time is exceeded.

A.

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

I know that this is a somewhat old thread but am working on this same item right now. I first of all wanted to confirm AXM1955's statement that there is a controller involved. Quite a complex setup for what would at first thought be a simple system. As my existing unit is corroded from a water leak there is some conjecture in the following:

There is only one pressure/vacuum line running into the system. Vacuum causes all of the door locks (except driver), the fuel cover, and supposedly the trunk to lock (edit - verified that trunk does lock but does not unlock). Removing vacuum and on my car all the items remain locked. Adding pressure to the line on my vehicle causes the fuel cover to unlock. Venting to atmosphere does nothing.

The circuitry appears to have a timer IC. There is also a pressure switch that will trigger on either vacuum or pressure. It appears that the motor will activate and run until either the time runs out or the pressure switch is tripped.

My questions are:

1) What is supposed to "power" unlock? The fuel cover only, the cover plus the trunk, or everything including the doors?

2) How is the unlock sequence triggered? Merely removing vacuum or does the system require pressurization? It appears to require pressure based upon the action of the fuel cover in my vehicle, the overpressure switch on the pump, and that there doesn't appear to be an electrically activated pressure release in the system.

1)Trunk, fuel door, all doors

2)IIRC There is an electronic switch in the drivers door lock (and in later models I believe the trunk) that triggers the pump to lock/unlock. If the pump runs too long with out building up (leak) then it will time out and no longer work when triggered until it is reset by disconnecting the battery.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

>> 1) What is supposed to "power" unlock? The fuel cover only, the cover plus the trunk, or everything including the doors?

>Trunk, fuel door, all doors

Strange. Everything but the doors unlock. At what pressure are they supposed to trigger? Note that the system holds both a vacuum and pressurization. There do not appear to be any leaks. It seems strange that all of the doors would fail in the exact same manner with no leaks.

>> 2) How is the unlock sequence triggered? Merely removing vacuum or does the system require pressurization?

> )IIRC There is an electronic switch in the drivers door lock (and in later models I believe the trunk) that triggers the pump to lock/unlock. If the pump runs too long with out building up (leak) then it will time out and no longer work when triggered until it is reset by disconnecting the battery.[/QUOTE]

??? This doesn't appear to answer the question. Right now I am working under the assumption that the unlock sequence requires pressurization as that is how the fuel door is triggered. Perhaps a rewording will help. To start the unlock procedure for the related items does the pump just vent the system or does it pressurize? If it pressurizes what is the pressure required?

It pressurizes. I'm not sure to what pressure though.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

> It pressurizes. I'm not sure to what pressure though.

Thanks. That does help a lot. I tried hand pumping the system with a Mityvac in the output port to ~20 psi with the results noted above (doors do not unlock.) I'll test a pump when I get a replacement and post the results here.

Hello all,

Gene I apologize for not posting a resolution to my issue, but here it goes.

My problem turned out to be a corroded connector near the pump motor, my rear windshield gasket leaks causing water to collect into the trunk especially in the spare tire area where MB placed said door locking/unlocking pump. After wasting a couple of day's diagnosing "pump failure issues" one evening (while I had the device on the bench) decided to power it up and play door lock with a jumper. When the pump worked I presumed I was wasting my time and started looking for "connections issues" in the car and found the above (solder and heat shrink tubing + moving the pump to higher ground worked well for me).

The test: If you have a battery charger get a couple of small alligator clipped leads to connect to your pump input plug (the rectangular plug to pumps edge) make sure the +12v lead id clipped on where the plugs red wire would be. With these in place and the charger on, get another jumper PAIR of jumper leads and connect one to the charger + (leave other end unconnected) and the other to the charger - (again leave other end unconnected).
Opposite of the power connector there is a round receptacle where your door lock/unlock wires go to. First take the + jumper and connect to one by one the three plug pins. When the pump starts running leave the jumper connected, then take note of which pin it is. Feel if air is being pushed out or sucked in on the tubing connector (also note this). Next put your finger over the port and note how much pressure your finger puts on the opening to stop the motor. Repeat for the process for the - wire noting that the round plug which activated the pump with the + can be bypassed (works for the +). End pump test.

Now for your doors unlock issue.

You have a leaky pipe, pipe to other pipe connector or door pod leak issue. First follow the yellow Tygon tubing from the pump, it should split with a a rubber T, one end toward your fuel lock, the other toward the front of the car. You have already established that that connection works (see your input above) so proceed to the interior of the car. Remove the RR door seal plate pull RR carpet up and look in the tubing channel for the infamous yellow tubing if it splits there (RR and RL doors) pick a side unplug the hose cap the open port return to the rear and repeat your vac/pressure test and see if your RR or RL door locks and unlock. Reinstall all pieces, continue forward to the RF flooring there is another T there for RF door. Repeat test till you find your culprit.

In my case the RF door pod turned out to be the pain on my back side.

Best regards and good luck.

Adriano

__________________
Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

Anyone tried to put this electric vacuum pump to a w123? What are the parts needed aside from the pump?

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles