A number of years ago I fitted one of those 3 bulb conversion kits to my taillights for extra brightness. Well, that extra brightness turned out to be drawing about 10 amps and this is what most probably fried my stop light pressure switch   
I have since purchased LED taillights, to fix the issue.
With the stop light pressure switch. It is mounted to the adjustable proportioning valve. I have to remove it and swap it out, but cannot work out what people use to remove/replace them. None of my sockets fit. It seems to be a very strange size. Can anyone please share what tool needs to be used to remove this? It is in a real tight spot too as I have it all connected up and I REALLY do not want to remove the adjustable proportioning valve.
Thanks

 

Last edited by Stevo (10/14/2017 11:41 PM)

flamingpony wrote:

Just a thought Stevo but have you tried any metric wrenches ,you know how the auto people like to mess with our heads. 

Thanks for the post.
I tried the metric range and it seems to be something like a 25mm? I do not have one of these sized sockets and went to the local auto store and all they had were sizes up to 24mm and then it skipped 25mm and 26mm and continued on from 27mm.
Quite frustrating...
 

MS wrote:

I use a large crescent wrench, but I realize your space limitations.

I was worried this might be the case... Is this the only option? Does anyone know if a socket will fit? It nearly looks like a 25mm socket will fit it? Maybe?
Hoping to not have to pull the lines and adjustable proportioning valve out as this will be a real pain.
If a socket is not an option... How tight are these switches when done up? There may be an ever so slight chance that I can latch a set of multi-grip pliers onto the thing and loosen it to where I can wind it off by hand.
How much brake fluid do you think I am going to lose?
Thanks.
 

If you leave the master cylinder lid attached and do not push the brake pedal, you will not lose hardly any fluid.  No rebleeding will be necessary most likely.  The fitting has a 1/8" pipe thread and is not usually that tight, but you should use a crescent wrench on the valve body to keep from moving while you remove the switch.  Check under the switch body.  Some might have a 1/2" hex under there.

MS wrote:

If you leave the master cylinder lid attached and do not push the brake pedal, you will not lose hardly any fluid.  No rebleeding will be necessary most likely.  The fitting has a 1/8" pipe thread and is not usually that tight, but you should use a crescent wrench on the valve body to keep from moving while you remove the switch.  Check under the switch body.  Some might have a 1/2" hex under there.

Thanks for the heads up on this. I was planning to do it this way. Technically, it should not need re-bleeding as you say. I will check to be certain though...
Fitting the socket in this really tight area will be the big test. I have the adjustable proportioning valve directly under the master cylinder as I thought this was the best place for accessibility. The pressure switch is so close to the brake lines and fittings though.
 

Stevo wrote:

FYI - I have learned (from an Automotive Electrician) that this is a really bad idea

https://www.lamustang.com/Content/generated-images/parts/original/6526_o.jpg

He advised me this creates such a massive current draw and is not good at all...
 

 
Like most modifications, it depends on how you do it. If you just replace the single bulb tail lights with triple bulb, then you triple the current on the stock wiring. If you add a relay to the tail light and flasher circuits with a suitable power wire, then it is perfectly safe. Automotive electrician?