brake light switch

[pflaming]

Does it make any difference which way the wires are connected to the switch? The poles atop the switch are different, one requires a bullet the other a 'slip on'. Would the way it was hooked up have an effect on it's longivity? Been reading about the short life of these switches, discouraging. One might put a small bulb on the dash that lights up with braking, if it doesn't light up you know the switch is bad.

[B1B Keven]

Doesn't matter Paul. It's just making a complete circuit when the brakes are applied.

[Merle Coggins]

Correct, it doesn't make a difference. However, I don't ever recall seeing a switch with two different type of connections. Regardless, the switch only connects the two contacts to complete the circuit, so there is no polarity requirement.

I finally gave up on the Napa switches and got one from Rock Auto. Since then I haven't had any problems.

And there's an easy way to test if it's working. Just step on the brake, before starting the truck, and watch the ammeter. If the switch, and brake lights, are working your meter will jump to the negative side slightly. If the needle wiggles the brake lights are working, start 'er up and go for a drive.

Merle

[Don Coatney]

And there's an easy way to test if it's working. Just step on the brake, before starting the truck, and watch the ammeter. If the switch, and brake lights, are working your meter will jump to the negative side slightly. If the needle wiggles the brake lights are working, start 'er up and go for a drive.

Merle

That test no longer works in my P-15 as I have light emitting diode brake lights. They do not draw enough current to bounce the meter.

Another way to test your brake lights from back in the day is to turn the key on, then turn the radio on and let it warm up. Once it is warmed up turn the key off but leave the radio turned on. Then turn the turn signal on to either right or left position and step on the brakes. The radio will play each time the turn signal flashes. Take your foot off the brake and the radio will quit. Trust me this works. Feedback welcome (pun intended).

[Bradley S.]

Great tip Merle! I am going to use that.

[TodFitch]

Great tip Merle! I am going to use that.

Another advantage of Merle's test is that you verify that you have proper brake pedal feel before moving the vehicle. Master cylinder had gone out on my '33 since the previous time I'd driven the car and that brake light check kept me from driving the car until I got it fixed. Hate to think what would have happened if the first use of the brake was going down the driveway on in the road.

p.s. Retail cost at my local hardware and auto supply stores for all the parts needed to make up a pressure bleeder (1/2 gal garden sprayer, bolt on Schrader valve, clear tubing, brass fittings for adapter, etc.) was about $20. Money well spent. Used the Schrader valve and tire chuck on air hose to pressurize because the hand pump on the sprayer has its outlet on the bottom and I was worried about getting air bubbles into the DOT5 fluid. If you're using DOT3 or DOT4 you probably wouldn't have to worry about that.