| swelchy |
Sun Jan 22, 2017 5:58 am |
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Any body that can explain how I can test to rule out if the brake circuit switches are bad or the wiring is bad?
P.O. does have some funky wiring stuff and I've been fixing connections here and there for two years when doing work.
o.k. I have 1969 Bay has 2 each of the 3 prong brake switch
red/black striped wire confirmed its going to a termianl on hazzard switch
has two black wires leaving the switches with the red black... confirmed one is plugged into brake check light... the other black im not sure yet where its terminating... Any who
running lights work
blinkers work
hazzards work.
What do I hook up to test the switches or another thread talks about jumper wires but I really want to be sure what to jump to test so I dont melt crap up.... |
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| swelchy |
Sun Jan 22, 2017 9:18 am |
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| :idea: |
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| aeromech |
Sun Jan 22, 2017 10:01 am |
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| I've placed a switch in my vise. Hook up the ohm meter to it and use shop air to actuate the switch |
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| swelchy |
Sun Jan 22, 2017 10:04 am |
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| Aeromech... any way to connect a temp jumper wire to the switch connector to trick the wiring to think the brakes are applied so I can check to see if the brake lights illuminate? this would let me know if the wiring is set up correctly and the switches are bad right? this way Im not messing with losing fluid pressure on the master cylinder at this moment.... |
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| busdaddy |
Sun Jan 22, 2017 10:05 am |
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Are you sure it's red with a black tracer and not black with a red tracer? On a properly wired system jumping between the black and black/red when the key is on will light the brake lights.
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| aeromech |
Sun Jan 22, 2017 10:14 am |
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| Yeah, just touch two wires from the switch together |
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| swelchy |
Sun Jan 22, 2017 4:59 pm |
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| okay thans... I had to stop for the day and didnt get a chance to try it... but i did get a meter on the back of the check switch.... wire from fuse box is getting 12v at the connection one wire is grounded and the other black wire that leads down to mc switches is reading 2.4 volts.... do both wires need to be reading voltage? |
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| telford dorr |
Sun Jan 22, 2017 5:37 pm |
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From the schematic (above), each switch originally had three wires. These wires connect to the same terminals on both switches:
- black, from fuse - measures 12 volts to ground; if shorted, the fuse blows.
- black/red, to (indirectly, via 4-way flasher switch and turn signal switch) brake lights - measures 0 to ground; if connected to the black wire, the brake lights will light.
- red wire, to brake check lamp; if connected to black wire, the brake check lamp on the dash will light. (Sounds like this wire is black on your bus.)
Curiously, if you jumper all three wires together, both the brake lights and the dash lamp should light. Thus, you can't (theoretically...) screw up.
If your wires are different than this, you're gonna have to trace back into the harness and see where they go. |
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