Door Light/Buzzer Switch - PeachParts Mercedes-Benz Forum

toddyvol · #1 11-25-2010, 11:40 AM

Both of my driver and passenger door switches are intermittent. I took both out and tried to clean the contacts with alcohol. I did not take them apart for fear of breaking them and was unsure on how to do so. Is it possible to disassemble the switches and if so how? What inside the switch would cause it to not make proper contact?

I did swap the switches which seemed to help. I can twist the button and it makes the light come on. Wires look good, what I can see of them do.

Can new switches be bought?

Should I try contact cleaner?

Jeremy5848 · #2 11-25-2010, 01:25 PM

I've not had the problem you are experiencing. Mercedes generally makes (or subcontracts) parts that can be disassembled and this switch is no exception. If you will remove one switch from the car and examine the base (where the wires clip on) you will see two tabs that hold the guts to the body. These can be pried apart to take the switch apart. The metal components can then be cleaned. Note that they are silver-plated and should be cleaned with a metal polish and a q-tip rather than steel wool or sandpaper. I use Mother's Mag and Chrome Wheel Polish only because I have it around for car stuff. You can also use household silver polish.

New switches are available. Click the "Buy Parts" link at the top of the page and patronize the good folks who support this web site.

Not only can you buy new switches, you can get the new design in which the plunger can be pulled out into a locking position. This allows you to have the door open with the key in the ignition (while you are doing some kind of test on the car, for example) without having to listen to the buzzer.

Edit: As MBeige notes in the next post, the new switches have a gray plunger while the original ones (non-locking) have a black plunger. They occasionally turn up in junkyards, especially as trunk light switches.

Jeremy

MBeige · #3 11-25-2010, 01:39 PM

Quote:

Originally Posted by Jeremy5848

I've not had the problem you are experiencing. Mercedes generally makes (or subcontracts) parts that can be disassembled and this switch is no exception. If you will remove one switch from the car and examine the base (where the wires clip on) you will see two tabs that hold the guts to the body. These can be pried apart to take the switch apart. The metal components can then be cleaned. Note that they are silver-plated and should be cleaned with a metal polish and a q-tip rather than steel wool or sandpaper. I use Mother's Mag and Chrome Wheel Polish only because I have it around for car stuff. You can also use household silver polish.

New switches are available. Click the "Buy Parts" link at the top of the page and patronize the good folks who support this web site.

Not only can you buy new switches, you can get the new design in which the plunger can be pulled out into a locking position. This allows you to have the door open with the key in the ignition (while you are doing some kind of test on the car, for example) without having to listen to the buzzer.

Jeremy

Jeremy, great post! Yes, the updated switch has a gray "pin" with slots on the pin for the fingers to make it easier to pull it out.

I have this switch replace all door and trunk switches on my W123 and W201.

The W123 trunk switch bracket will not accept the updated switch. The original trunk switch is different in that it is shorter so the bracket has a "brace" for this. However, the original W201 trunk switch bracket will fit the W123, and will accept this updated switch.

Jeremy5848 · #4 11-25-2010, 02:42 PM

Quote:

Originally Posted by MBeige

Jeremy, great post! Yes, the updated switch has a gray "pin" with slots on the pin for the fingers to make it easier to pull it out.

I have this switch replace all door and trunk switches on my W123 and W201.

The W123 trunk switch bracket will not accept the updated switch. The original trunk switch is different in that it is shorter so the bracket has a "brace" for this. However, the original W201 trunk switch bracket will fit the W123, and will accept this updated switch.

When I had a 123, I didn't replace the trunk switch because I didn't know about the 201 trunk bracket. Thanks for that great tip. My 124 has the new switch in seven (!!) locations and if I end up using the alarm switch for an under-hood light (my alarm was removed by a PO), I may end up installing an eighth.

MBeige · #5 11-25-2010, 08:53 PM

Quote:

Originally Posted by Jeremy5848

When I had a 123, I didn't replace the trunk switch because I didn't know about the 201 trunk bracket. Thanks for that great tip. My 124 has the new switch in seven (!!) locations and if I end up using the alarm switch for an under-hood light (my alarm was removed by a PO), I may end up installing an eighth.

Seven locations? I can only see 7 total for the car (doors = 4, trunk = 1, hood = 1, glovebox = 1). Where will the eighth one go?

toddyvol · #6 11-25-2010, 09:17 PM

Quote:

Originally Posted by Jeremy5848

I've not had the problem you are experiencing. Mercedes generally makes (or subcontracts) parts that can be disassembled and this switch is no exception. If you will remove one switch from the car and examine the base (where the wires clip on) you will see two tabs that hold the guts to the body. These can be pried apart to take the switch apart. The metal components can then be cleaned. Note that they are silver-plated and should be cleaned with a metal polish and a q-tip rather than steel wool or sandpaper. I use Mother's Mag and Chrome Wheel Polish only because I have it around for car stuff. You can also use household silver polish.

New switches are available. Click the "Buy Parts" link at the top of the page and patronize the good folks who support this web site.

Not only can you buy new switches, you can get the new design in which the plunger can be pulled out into a locking position. This allows you to have the door open with the key in the ignition (while you are doing some kind of test on the car, for example) without having to listen to the buzzer.

Edit: As MBeige notes in the next post, the new switches have a gray plunger while the original ones (non-locking) have a black plunger. They occasionally turn up in junkyards, especially as trunk light switches.

Jeremy

For some reason I can't find 'em at Fastlane.

Sev · #7 11-25-2010, 10:30 PM

"Seven locations? I can only see 7 total for the car (doors = 4, trunk = 1, hood = 1, glovebox = 1). Where will the eighth one go?"

storage compartment of the armrest

Jeremy5848 · #8 11-26-2010, 12:57 AM

Quote:

Originally Posted by MBeige

Seven locations? I can only see 7 total for the car (doors = 4, trunk = 1, hood = 1, glovebox = 1). Where will the eighth one go?

Front doors, 2 each, total 4 (1 for interior lights, alarm, buzzer, etc.; 1 for power seats)
Rear doors, 1 each, total 2
Trunk, total 1
Hood, total 1
Grand total 8 (I didn't count the glovebox, thanks for the reminder)

It is possible that later 124s had more sophisticated electronics ("convenience modules") and got along with one switch for each front door. My '87 needs 2 as shown in the attached picture, taken while I was replacing the dash in 2009. I had upgraded one of the switches but the other was still the old style. Since then I have upgraded all of them.

Is there a locking version of the glovebox switch available?

Jeremy

MBeige · #9 11-26-2010, 02:24 AM

Quote:

Originally Posted by Jeremy5848

Front doors, 2 each, total 4 (1 for interior lights, alarm, buzzer, etc.; 1 for power seats)
Rear doors, 1 each, total 2
Trunk, total 1
Hood, total 1
Grand total 8 (I didn't count the glovebox, thanks for the reminder)

It is possible that later 124s had more sophisticated electronics ("convenience modules") and got along with one switch for each front door. My '87 needs 2 as shown in the attached picture, taken while I was replacing the dash in 2009. I had upgraded one of the switches but the other was still the old style. Since then I have upgraded all of them.

Is there a locking version of the glovebox switch available?

Jeremy

It's been a while since I looked in the glove box of our 300TE but I think I remember seeing a gray pin switch in there.

I didn't realize the front door 2nd switches were for the seats. Always wondered what they were for. Thanks for that info!

I only placed the gray pin switches for the dome light, since I don't think I have any reason to use that type of switch for the electric seat adjustment.

Jeremy5848 · #10 11-26-2010, 12:06 PM

Quote:

Originally Posted by MBeige

It's been a while since I looked in the glove box of our 300TE but I think I remember seeing a gray pin switch in there.

I didn't realize the front door 2nd switches were for the seats. Always wondered what they were for. Thanks for that info!

I only placed the gray pin switches for the dome light, since I don't think I have any reason to use that type of switch for the electric seat adjustment.

The reason you want a gray-pin switch in the power seat position is because when either front door is open, a relay (K5, the Power Seat Relay) in the fuse/relay box is powered up, drawing some current from your battery. In a quiet location, press that switch (only one front door can be open for this to work) and you will hear the relay click off.

Granted that it will take days with the door open for that load to run down a healthy battery, I prefer that I be able to control all electrical loads at my own whim.

Jeremy

MBeige · #11 11-26-2010, 12:57 PM

Quote:

Originally Posted by Jeremy5848

The reason you want a gray-pin switch in the power seat position is because when either front door is open, a relay (K5, the Power Seat Relay) in the fuse/relay box is powered up, drawing some current from your battery. In a quiet location, press that switch (only one front door can be open for this to work) and you will hear the relay click off.

Granted that it will take days with the door open for that load to run down a healthy battery, I prefer that I be able to control all electrical loads at my own whim.

Jeremy

Ah, I see now!

Thanks Jeremy.

Stevo · #12 11-26-2010, 01:12 PM

Good upgrade, I didn't know such a thing was available, thanks.

MBeige · #13 11-28-2010, 06:36 PM

Quote:

Originally Posted by Jeremy5848

The reason you want a gray-pin switch in the power seat position is because when either front door is open, a relay (K5, the Power Seat Relay) in the fuse/relay box is powered up, drawing some current from your battery. In a quiet location, press that switch (only one front door can be open for this to work) and you will hear the relay click off.

Granted that it will take days with the door open for that load to run down a healthy battery, I prefer that I be able to control all electrical loads at my own whim.

Jeremy

Jeremy,

I was toying with my mother's '90 300TE and it does not have a second door jamb pin/switch on the front doors. So I pulled the gray pin switch it has and the electric front seat stopped working. Maybe they combined both functions around that year onwards.

Jeremy5848 · #14 11-28-2010, 08:30 PM

Somewhere around that year Mercedes added another "convenience relay." This probably allowed them to delete one of the door switches. This may have also been when the function was added that allowed you to close all of the windows and sunroof by locking the car from the outside and holding the key in the "lock" position for a few seconds.