Turn indicator & brake light continuous flashing, Started with a bad bulb Options

[bzettner]

'73 1.7, driving along (IMG:style_emoticons/default/driving.gif) both dash turn indicator lights and brake light started flashing continuously (IMG:style_emoticons/default/WTF.gif) . Found out I had a burned out turn signal bulb. Did my 914World searching and learned the flashing is to "let you know" you have a bulb out, great! Changed out the bulb, flashing continues. Cleaned light socket contacts, bulb ends, changed out bulbs in matched pairs, replaced flasher unit with new RockAuto unit, still continual flashing. Added a little brake fluid, no change.

All my lights work as designed, all of them. Dash turn indicators are bright and work individually when used. The new flasher unit causes the dash indicators to flash continually dimmer than the original unit.

I have found a white w green strip wire near the flasher unit that has no connection, no fitting, just a blunt cut wire with no obvious "answer" to its placement. I am NOT a great schematic guy (IMG:style_emoticons/default/headbang.gif) . Something changed! Ideas?

[bzettner]

@spoke

With the wires disconnected from the MC switch, measuring ohms from one prong to the other barely makes the needle on my meter move (high resistance). My switch is of the "not resettable" variety, 2-wire. So either the switch is faulty or perhaps it has done its job and something has changed on my braking system? My brake feel and stopping power is equal to what it has always been.

Ignorant master cylinder question, can the switch be changed out without brake fluid loss? Will this be a brake bleeding session after the switch change?

[Spoke]

@spoke

With the wires disconnected from the MC switch, measuring ohms from one prong to the other barely makes the needle on my meter move (high resistance). My switch is of the "not resettable" variety, 2-wire. So either the switch is faulty or perhaps it has done its job and something has changed on my braking system? My brake feel and stopping power is equal to what it has always been.

Ignorant master cylinder question, can the switch be changed out without brake fluid loss? Will this be a brake bleeding session after the switch change?

Sounds like the switch is high resistance. It should be infinity. The needle should not move if the switch is open. What resistance do you measure? If you have an older volt-ohm-meter it's a bit more difficult to determine an accurate measurement.

If you have difficulty determining the actual resistance just take a picture of the VOM during the test. I don't mean to insinuate you don't know how to read the meter but they can be tricky. I worked with a guy once who claimed an LED that I made didn't work because there was 12V on the meter. I said the wires might be reversed and the voltage backwards. He finally showed a picture of the VOM and indeed the measurement was -12V instead of +12V.

Also while you're there, try measuring each of the 2 switch terminals separately to chassis ground to see if either terminal has a leakage path to chassis ground.

About replacing the switch, it is likely that if the switch is removed fluid will escape and the system would need a full bleed. I'm not familiar with replacing just the switch. Maybe someone could chime in with some experience with switch replacement.