brake light switch

[tttuba]

Once again I come to the people that know.....I have a 47 that the previous owner put power brakes on. I am changing the wire harness since the prior owner also did a horrible job with the wiring....all the same color. So my question... is there a brake light switch on the vehicle somewhere or could it be this thing I found in the middle of the brake line which has 2 wires coming off of it? Kind of looks like this might be a switch activated by pressure in the line. But I have never seen anything like that before so I am confused.

[mr48chev]

That should be it, a 'Ford style brake light switch.

Probably quite similar to this one http://www.rockauto.com/catalog/rafr...185671-3146202

I have one on the 48 and usually have had to replace it about every other year. It isn't very expensive and is easy to find though.

[tttuba]

Kind of looks like that but when you replace it do you have to bleed the brakes?

[mr48chev]

It's a good idea. But if the truck has been sitting for any length of time you will probably need to bleed the brakes anyhow. Usually if you have the new switch ready to go in you don't loose a lot of fluid or get much air in the system.

Unscrew the old one, hold your finger over the hole, screw in the new one.

You should be able to cross the Standard SLS27 number at any parts house you go to. By clicking on the number you can see the applications and it fits a lot of different vehicles including some Jeep models up through 1973.

The thread should be 1/8" pipe but there may be a different size unit out there that I don't know about. NAPA link https://www.napaonline.com/Catalog/C...213430960&An=0

[solidaxel]

Originally Posted by mr48chev

That should be it, a 'Ford style brake light I have one on the 48 and usually have had to replace it about every other year. It isn't very expensive and is easy to find though.

In the past I have used these switches but I found out by using a relay to switch the pressure switch lasted until I sold the truck (3 Years).

I have also used a motorcycle H.D. switch which is the same size and uses 12VDC also

[mr48chev]

Originally Posted by solidaxel

In the past I have used these switches but I found out by using a relay to switch the pressure switch lasted until I sold the truck (3 Years).

I have also used a motorcycle H.D. switch which is the same size and uses 12VDC also

I never thought about using a relay on the stop lights.

I have them on the headlights of the 71 and they will be on the 48 when I do the rewiring.

[solidaxel]

Originally Posted by tttuba

Kind of looks like that but when you replace it do you have to bleed the brakes?

Depends on how long it takes to screw in the new switch and how much fluid you lose when you remove the old switch.
Is the switch on the rear brake line or at the master cylinder?

[tttuba]

It is in the rear brake line on the truck frame rail

[solidaxel]

Be quick and don't cross thread it, you will be O K !!