brake light switch diag

[tow hook]

i lost my brake lights on the Saturday ride in Gettysburg. so i'm trying to diag. my switch. the  service manual is no help, " is its bad , replace it "   i have both rear running lights, and rear turn signals. so i would say the bulbs are fine. i used a12volt test light, on the switch an no reading. with the brake pedal  pressed down. i checked the wires that go to the switch ( i assume power goes just 1 side ) and if i put the meter between both wires i would get a reading. i got 12 volts from that test ,so it's fair to assume that the switch is bad ? 

it's a pain to bleed the brakes, and just wanted to make sure i'm on the right path. any thoughts

thanks for the input

[Rus Curtis]

That test of the tail and then turn lights would confirm both filaments are functioning.  You could have also shorted across the wires or disconnected them and touched (effectively removing the switch) and observed your brake lights. They should illuminate as power is bypassing the switch.

I would also assume your switch is bad.  There shouldn't be much fluid that leaks out when you remove it. I recall swapping mine out without bleeding - but you can also screw in the new one, apply some pressure (not a lot) and slowly back out the switch until fluid drips/squirts out and then screw back in to seal before releasing the pedal.  That may eliminate the need for a full bleed.

Those switches can be temperamental, just like the condensers.  Buy a good brand vs. something you don't recognize.

Some have converted to a manual switch to avoid this but that was one of the first things I removed back in the day to return it to original. 

BTW, I just replaced a bad backup light switch for the same reason.  Lasted about a month or two and went bad.

[tow hook]

thanks for the info.(  i did jump the wires, with the key in the run position) switch is bad,  looks like ebay or k.w. for a new switch

[Rus Curtis]

Before you order, suggest taking yours into a local parts store and see if they have it (there's maybe 3 different terminal types).  I have had hit and miss on certain parts when ordering and you can't walk it back in if it fails.

If ordering is your only option, search for "best" hydraulic switches and see if a brand is listed that you have access to.

[tow hook]

Before you order, suggest taking yours into a local parts store and see if they have it (there's maybe 3 different terminal types).  I have had hit and miss on certain parts when ordering and you can't walk it back in if it fails.

If ordering is your only option, search for "best" hydraulic switches and see if a brand is listed that you have access to.

thanks, auto zone doesn't carry them any more, and the napa wed site wouldn't list a picture and it was double the cost every were else.

[elawson]

I'm looking in the NAPA web site and I see a brake light (they call it "stoplight switch") switches with various wire hookup terminals.

Check out the following NAPA part numbers.  As near as I can tell, all have the 1/8-27 NPT part to screw into the brake cylinder and, hopefully, one of the terminal configurations is what you need.

MPE SL134
MPE SL147
ECH SL139
ECH SL133
ECH SL136
ECH SL113
ECH SL142

 

[tow hook]

I'm looking in the NAPA web site and I see a brake light (they call it "stoplight switch") switches with various wire hookup terminals.

Check out the following NAPA part numbers.  As near as I can tell, all have the 1/8-27 NPT part to screw into the brake cylinder and, hopefully, one of the terminal configurations is what you need.

MPE SL134
MPE SL147
ECH SL139
ECH SL133
ECH SL136
ECH SL113
ECH SL142

 thanks i will check it out

[Mark W.]

Another way to fix this and not have to bleed the brakes is to install a mechanical brake light switch. It would mount to the master cylinder access cover and the arm on the switch will rest on the brake pedal arm.

https://www.napaonline.com/en/p/ECHSL128

you have to do a little experimenting to get the mounting position right but well worth it as they are a MUCH better switch then the Hydraulic ones.