Brake Light Switch testing.

[RICKG]

What's the correct way to test the brake lite switch?
Thx, Rick
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

[Jeeps4Brains]

If it is off the truck I have rigged up a way to put it under air pressure. I just figured out a series of fittings to attach an air hose to it.

Then I hooked a meter to it and checked to see it it closed the circuit.

If it is on the truck disconnect the wire connection and put your meter leads to the connections and get someone to push on the brake pedal for the pressure and see if the switch closes. That assumes your brake master cylinder is good and can create pressure.

Alan

[RICKG]

Thanks Alan, so i should read zero ohms between the 2 pins with the
pedal pushed down?? (units on the truck).
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

[Bretto]

Yep, and open ckt (infinite ohms) when pedal released. Sometimes you might get 1-2 ohms depending on your meter. Mine reads 2 when I touch the leads together. Its a cheapy.
_________________
Brett
'51 M38
PHOTO DIARY OF MY BUILD

[RICKG]

Switch tested good. I'd like to continue this thread- i have no brake lites.
The harness that came w/the jeep is a repop, was loose-not bagged and no paperwork with it. At the steering column there's 4 loose wires- 22-460, 22-461, 460-461, 22. 460-461 and 22 read 24V hot.
Both #75 wires to the B/L switch read 24V w/light switch off.
I installed a signal stat flasher system early on and fashioned its own dedicated harness so its not connected to the main harness. I installed gama goat lenses and have 3 lamp fixtures both rear sides. Tail/marker and directionals work. Point me in the right direction in my troubleshooting-electrical understanding is not my strong suit. I prefer to use only the svc
side of my 3 lever switch. Sorry for the long wind..
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

[Jeeps4Brains]

The 460-461 is usually the wire that goes from the light switch J plug to whatever turn signal control unit you have.

The 22 is the stop light wire. On stock military taillight setups the 22 wire will run to the rear driver’s side for the single stop light.

The 461 is the driver’s side turn circuit. The 460 is the passenger side circuit. Front and back on both these.

If you have separate tail, turn and stop bulbs then the 22 needs to go to whatever stop light bulb connections you have.

The 22-460 and 22-461 are a combination turn and brake feed to a combined turn and stop bulb. But you need to have a control box to manage when power goes to which bulb. It is easier to just have three separate bulbs on each rear side and have a flasher to control the turn bulbs.

[capescw]

Jeeps4Brains is correct, but if you're wiring the whole thing, you might want to copy this!

http://www.bill-capes.com/insanity/wire-numbers.txt

I submitted it, but it hasn't been released yet.

Enjoy !!
_________________
"Frugality keeps me in the Game"
1952 M38 Project "Lazarus"
1951(?) M100 Trailer
1956-60 USAF Special Weapons Program
http://www.bill-capes.com/insanity - Updated 04/26/14

[RICKG]

Guys, i've got the wire numbers-just dont know why i've got the 4 leads hanging down at the steering column. The (2) #75's are at the brk lite switch ok. my signal stat 900 turn signals are on a separate dedicated harness not attached to the main harness in any way. All lites except the brake lites work fine.
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

[Bretto]

Ok Rick,
With the switch moved to stop light position, it should put battery at either pin A or K, I can't remember (wires 75) then that goes to the brake switch then when the switch is closed, it will feed battery back into either pin A or K of the switch. A and K wiring can be flipped so it doesn't matter it's orientation. When that all happens, you should get battery out of pin C (wire 22) that feeds the stop bulb(s). Anything after pin C is wiring to the bulb. Not sure why you are seeing +24 on both 75's with the brake switch open. With it closed yes as one is bringing 24V to the brake switch and the other is the return path to the light switch. i wish I were closer so I could get my hands on it.
Brett
_________________
Brett
'51 M38
PHOTO DIARY OF MY BUILD

[capescw]

Assuming there are still problems, this is one from Wes's photo gallery:

http://www.willysmjeeps.com/v2/modules.php?set_albumName=album85&id=Wring_Diagram&op=modload&name=gallery&file=index&include=view_photo.php
_________________
"Frugality keeps me in the Game"
1952 M38 Project "Lazarus"
1951(?) M100 Trailer
1956-60 USAF Special Weapons Program
http://www.bill-capes.com/insanity - Updated 04/26/14

[RICKG]

[STXM38A1]