claybill Posted August 26, 2009 Report Share Posted August 26, 2009 no brake lights..checked everything, it has to be in the brake lite switch..WAIT..where is it,? looked everywhere..hey its dark under that car..(and everything is 3-4 inches from my face)..ha ha ! checked the wiring at the headlite switch and all looks ok all over. checked the wiring in the trunk..looks ok. bulb is good. switched wires with tailight and brake lite AT THE CONNECTOR..and it works. it must be a faulty switch. there was some current coming thru, but the circuit tester was very dim, and now there is no light in the c/tester. bill Quote Link to comment Share on other sites More sharing options...
paulmusiclover Posted August 26, 2009 Report Share Posted August 26, 2009 Bill - in my '48 - the brake light switch is under the hood, under where the steering column comes out of the firewall, it has two blue wires coming out of it. hope this helps! Paul Quote Link to comment Share on other sites More sharing options...
greg g Posted August 26, 2009 Report Share Posted August 26, 2009 It (the switch) is usually on the line coming out of the MC for the front brakes. The feed wire is unswitched as the brake circuit needs to be on regardless of whether the lights or ignition is on. I think mine is fed from the battery side of the starter relay/solenoid. If you can't find a feed that is a good place to pick one up. Quote Link to comment Share on other sites More sharing options...
claybill Posted August 26, 2009 Author Report Share Posted August 26, 2009 ok...so what makes the switch activate? is it something from pedal movement...a momentary on/off switch.....or brake fluid in a switch? i guess it can be quite remote from the pedal if it is activated by brake fluid..??@?@??$5???? early tomorrow it starts again. i gotta get brake lights!! going on a weekend trip with my teardrop in a few weeks.! bill Quote Link to comment Share on other sites More sharing options...
claybill Posted August 26, 2009 Author Report Share Posted August 26, 2009 paul...what activates it? is there some connection to the pedal movement/? bill Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted August 26, 2009 Report Share Posted August 26, 2009 Hydraulic pressure activates the switch. Quote Link to comment Share on other sites More sharing options...
P-12 Tommy Posted August 26, 2009 Report Share Posted August 26, 2009 (edited) Bill, It is a pressure switch. And like Greg says, it's usually right off the front of the master cylinder. Don's also correct. It has two small posts on it. Here's a picture. Sorry it's a little blurry. Tom Edited August 26, 2009 by P-12 Tommy Quote Link to comment Share on other sites More sharing options...
greg g Posted August 26, 2009 Report Share Posted August 26, 2009 lots of atv and motorcycles use similar switch, its a pressure switch activated by the brake flluid. Since teh fluid does pass through the switch some debris can negetively effect it's operation, by reducing pressure in the switch. If you nee a new one check your local Harley dealer. If you need ot change it unscrewing the old one and putt he new one in quickly and you should not need to bleed the brakes as what ever brake fkuid that escaps will prevent air from entering. Quote Link to comment Share on other sites More sharing options...
Phil Martin Posted August 26, 2009 Report Share Posted August 26, 2009 switch on my 50 Dodge coronet is in brake line just ahead of rearend. Took some looking to find it. Quote Link to comment Share on other sites More sharing options...
claybill Posted August 26, 2009 Author Report Share Posted August 26, 2009 ok...now i know what i am looking for. and where. thanks all. bill Quote Link to comment Share on other sites More sharing options...
Young Ed Posted August 27, 2009 Report Share Posted August 27, 2009 Bill look at the front of the master at the junction for the flex line in front of the rear end and at the junction block for the 2 lines to the front wheels. Thats the only places I've seen them. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted August 27, 2009 Report Share Posted August 27, 2009 To stop any potential fluid from coming out the brake line I put a block of wood behind the brake pedal and then wedge it against the floor board this will stop you from pressing the pedal and will also prevent it from slowing going down a pressing out fluid and stops the possibilty of getting any air into the brake line. Then clean around the brake switch were it screws into the MC or tee line to get all the crud removed from the areas, disconnect the two wires then unscrew the old unit screw inthe new unit attach the wires, remove the block of wood press the brake pedal and you should ahve brake lights. The fluid being pressing into the switch sends a small ball bearing up and then make contact with the top of the switch and then completes the cuircuit and send the electric to the brake lights very simple process. Rich Hartung desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
Roadkingcoupe Posted August 27, 2009 Report Share Posted August 27, 2009 Question? Does the use of silicon brake fluid negatively effect the lifespan of the brake switch? Has anyone confirmed this to be true? Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted August 27, 2009 Report Share Posted August 27, 2009 Question?Does the use of silicon brake fluid negatively effect the lifespan of the brake switch? Has anyone confirmed this to be true? I was having a problem with short life on some switches from Napa. They checked with their technical support people and one thing they asked me is if I was using DOT5 brake fluid because that was not compatable with their switches. Since I am using DOT 3 fluid that was not the reason for the short life of the switches. They didn't have an answer for me but they keep warrantying the switches. Speaking of that, I need to call them again since I still haven't got a replacement for the last failed one. Merle Quote Link to comment Share on other sites More sharing options...
blueskies Posted August 28, 2009 Report Share Posted August 28, 2009 ...One way to solve the short life of the pressure switch is to change over to a electric switch activated by the brake pedal.... I have the mechanical switch on my car. Put one on the clutch pedal too, for a neutral safety start switch. Pete Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.