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> Early 914 brake light switch
isdyl
post Sep 11 2018, 02:08 AM
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Hi, I'm have a difficult time obtaining a brake two pole brake light switch for my 914 here in the uk. It is a Bosch 0343102008 as seen in the photo with the mechanical plunger. It screws into the side of the master cylinder. Bosch have no stock and I have just found one available at a Porsche dealer for £80 which I am reluctant to spend. Mine is leaking and I have tried epoxy to repair it but no luck. I was thinking that there must be pressure in the plunger area when in operation as it leaks and forced past the epoxy, so could I use another two pole pressure switch provided it has the correct thread? (12x1mm I think). Has anyone else replaced their plunger type switch with an alternative? The later cars use a single pole 0343102010 which works in a similar way but I think grounds through the switch body when the plunger is pressed rather than connecting the two poles.


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Tbrown4x4
post Sep 11 2018, 02:26 AM
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I just replaced my M/Cylinder with a 19mm 914 Rubber one. It came with a single pole switch and it works fine. Just check the wiring diagram for which wire needs to be attached to it.
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isdyl
post Sep 11 2018, 02:54 AM
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Oh thats interesting thanks - maybe one of the wires is just an earth. I'll study the wiring diagram.
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isdyl
post Sep 11 2018, 03:09 AM
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QUOTE(isdyl @ Sep 11 2018, 02:54 AM) *

Oh thats interesting thanks - maybe one of the wires is just an earth. I'll study the wiring diagram.


No, it looks like one wire is a live supply from the fuse board and the other goes to the tail lamps. I think it needs to be a two connector switch.
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Tbrown4x4
post Sep 11 2018, 04:28 AM
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I'd check for you, but I'm at work.
What year are we looking at? I have a '73.


OK. Just remembered I have a wiring diagram in my car. I'm showing two inputs that turn on the brake warning light. The Parking brake contact and the "brake warning light switch", which should be the one on the brake master. The is a brown wire and a white with a brown stripes. I hooked up the white/brown wire to the switch and left the brown ground wire taped off.
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Tbrown4x4
post Sep 11 2018, 04:53 AM
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I don't think brake fluid should be coming out of the switch at all. There are seals on the "pistons" that actuate the switch when one circuit loses pressure. Maybe you are due for a new or rebuilt M/Cyl.
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isdyl
post Sep 11 2018, 06:01 AM
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Hi, Mine is an early '73 and I don't think it had a brake warning except for the switch under the parking brake to indicate the parking brake is on. The wiring diagram I was looking at is this one:

http://nicoh.me/porsche-914-wiring-diagram...ing-diagram-and

Item 35 is the switch on the master cylinder and I think it just mechanically operates the tail stop lights. It has 12v supply one side (shared by something else number 90) and supplies 12v to the tail lamps when pressed. I could be wrong?
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Tbrown4x4
post Sep 11 2018, 06:58 AM
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I think 35 is the switch on the brake pedal. What color wires are going to your switch?

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ClayPerrine
post Sep 11 2018, 11:36 AM
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QUOTE(isdyl @ Sep 11 2018, 03:08 AM) *

Hi, I'm have a difficult time obtaining a brake two pole brake light switch for my 914 here in the uk. It is a Bosch 0343102008 as seen in the photo with the mechanical plunger. It screws into the side of the master cylinder. Bosch have no stock and I have just found one available at a Porsche dealer for £80 which I am reluctant to spend. Mine is leaking and I have tried epoxy to repair it but no luck. I was thinking that there must be pressure in the plunger area when in operation as it leaks and forced past the epoxy, so could I use another two pole pressure switch provided it has the correct thread? (12x1mm I think). Has anyone else replaced their plunger type switch with an alternative? The later cars use a single pole 0343102010 which works in a similar way but I think grounds through the switch body when the plunger is pressed rather than connecting the two poles.



Just checking to make sure you are aware... the actual switch that lights the brake lights is located inside the passenger compartment on the pedal box. The switch you picture is for the brake failure warning light in the left hand gauge.

The two pole switch has been superseded by the single pole switch. Just buy the single pole, and leave the brown (earth) wire disconnected.
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isdyl
post Sep 11 2018, 11:51 AM
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Ah yes! Brilliant - thanks - this forum is excellent. I have just dug around under the peddles and seen the other switch. You have saved me a load of bother trying to get that 2 pole switch.

I actually wrote to Bosch last week saying I couldn't locate a 2 pole version and could I use a 0343102010. They couldn't have been less helpful - I'm actually quite annoyed by their 'couldn't care less' replies!
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ClayPerrine
post Sep 11 2018, 02:55 PM
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QUOTE(isdyl @ Sep 11 2018, 12:51 PM) *

Ah yes! Brilliant - thanks - this forum is excellent. I have just dug around under the peddles and seen the other switch. You have saved me a load of bother trying to get that 2 pole switch.

I actually wrote to Bosch last week saying I couldn't locate a 2 pole version and could I use a 0343102010. They couldn't have been less helpful - I'm actually quite annoyed by their 'couldn't care less' replies!


If you have to replace the switch, make sure the little arm is behind the big washer on the brake rod. The switch is held open by the brake rod, and closes with a spring when the brake is depressed.

Also be careful of wire routing to the brake light switch. You can accidentally get it in the way of the accelerator bell crank. That will pull the wires off the switch. And the MOT won't like that.

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isdyl
post Sep 12 2018, 01:23 PM
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Ok so the other switch isn't available either! Should I just blank it off with a plug? What does this switch actually do please? I think it's some kind of warning switch, and I spoke to someone today who thought it sent a message to the injection system not to provide fuel if the brake is pressed (?). I'm not sure its needed.
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bbrock
post Sep 12 2018, 02:33 PM
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You mean this one? https://www.amazon.com/Brake-Switch-PORSCHE...1/dp/B07932Y7H6

or this one?

https://www.ebay.com/itm/Brake-Light-Switch...675.c100623.m-1

Search on part numbers ( 91161341100 and 91461311600). Lots of options.
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isdyl
post Sep 12 2018, 02:39 PM
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Yes exactly those ones. I’ve ordered 3 so far but each time the seller has come back to me saying sorry they aren’t available. These guys just wait till they get an order and order it from Bosch. Bosch have none.
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bbrock
post Sep 12 2018, 02:46 PM
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QUOTE(isdyl @ Sep 12 2018, 02:39 PM) *

Yes exactly those ones. I’ve ordered 3 so far but each time the seller has come back to me saying sorry they aren’t available. These guys just wait till they get an order and order it from Bosch. Bosch have none.


Oh, that sucks. I'd contact 914rubber about the warning switch on the master cylinder. They include them on the master cylinders they make so are getting them from somewhere. It looks like they are both still available from Porsche but not cheap. Either could save your life though so I wouldn't delete them.
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914Sixer
post Sep 12 2018, 08:25 PM
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I have one. Contact me. It is also a stock VW Bug part. 113.945.515E
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isdyl
post Sep 13 2018, 10:39 AM
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QUOTE(914Sixer @ Sep 12 2018, 08:25 PM) *

I have one. Contact me. It is also a stock VW Bug part. 113.945.515E


That would be great, but I'm unfortunately in the UK. I called VW but unfortunately they stoped using them in the early '80's and they have been deleted of their system. Maybe its a UK problem - I may have to import one somehow.
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914Sixer
post Sep 13 2018, 03:34 PM
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Sent you a PM
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914Sixer
post Sep 14 2018, 12:44 PM
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I only have a clean used one. Yours for free now. Will get shipping later on today.


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isdyl
post Sep 14 2018, 02:49 PM
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Wow thats fantastic - thank you so much! I must give you something for it though - and the shipping.
Regards, Dylan
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