I've a '67 b-body. I replaced the master cylinder, and when I hooked up the brake light switch (switch was bench tested and current flowed through it) I had no brake lights nor parking lights; turn signal lights do not work. Fuses are ok; headlights work (though they are on relays). Question: when I disconnect the turn signal flasher, should there be power at the connector when the headlight switch is pulled on? I'm not getting power to the connector. I bench tested the turn signal flasher and when connected to a battery (9 volt) there was current running through the turn signal flasher (I guess this means it works?). Prior to replacing the master cylinder, everything worked.

The turn signal flasher should have power when the ign key is turned on in the run position. Hazzard flashers are hot all the time. Turn signals and brake lights go through the turn signal switch but the park lights do not as they are through the headlite switch. Ron

Update: did a search and a recommendation was to switch turn signal flasher with emergency flasher. I know have turn signals, but parking lights and brake lights still do not work. Suggestions, please.

Update 2: pulled connector off emergency flasher to get meter box probes in there. Had 10.6, 11.75 w/ eng idling, volts going to swapped in emergency flasher when turn signals engaged. Electrical systems are a weak area for me. I've the FSM and wiring diagrams. Where do I need to start? I'm thinking maybe the headlight switch is bad. Electrical problems frustrate the %$#@ out of me.

You have the basics correct , use your volt meter on the headlight switch to trouble shoot it It may be the switch or it might be in the bulkhead connector on the firewall or in the under dash wiring harness Let us know what you find

Update 3: pulled headlight switch, connected to battery (12 volt this time), grounded switch, put meter box to all connectors, measured a consistent 12.5 volts at all connections; had switch on and off-same readings. One item I noticed, when adjusting the switch to brighten or dim the instrument panel, there was no change in the volts. I'm thinking that there should've been because it is a rheostat switch (I think I'm right on calling it this).
I'm calling it quits for today. There's a margarita calling my name. Please continue to post suggestions. I'll be logged on in the AM. I want this car running. Having beautiful weather here in Texas, and I want to get out and enjoy it.
383man & Cab_burge, thank you for your replies and words of encouragement.
A final note: I'll purchase a turn signal flasher. I take it that they are easily obtained from the local parts houses.

Have you tried jumping the brake light switch wires to see if the lights work? That would eliminate one source of problems. Also check the parking light fuse to see if you have power on both ends with the headlight switch on. BTW do the parking lights come on when the headlight switch is in the parking light mode? Some of the earlier cars had the parking lights go out when the headlights were on.

This almost sound like a ground problem but with human interference, that is speculation.

Stop trying everything and anything, you'll just drive yourself nuts.

Let's break this down to systems. Stumpy is right, jumper the brake switch, what happens?

Yes he's right about the switch not always activating the park lights but I'm not sure what year that changed.

Stumpy is also right thyatvthe park fuse is hot on both sides when the headlight switch is set to park.

Short version, look for wires and connections you may have bumped while changing the master. It's more likely that you did something than wires crossed whom you changed the master.

take off the DR kick panel to access the connectors behind it. (1) Park light power originates in the HL switch then goes to the fuse box then down to the connector behind the kick panel for the rear park lites and to the bulkhead for the front park lites. (2) the brake light pedal switch is hot all the time (the pink wire) & this pink wire originates at the fuse box then goes to that switch & the white wire from the pedal switch goes to the TS switch assy in the column, then out from there down to the kick panel connector. (from the kick panel rearward for the brake lights you are good cuz the flashers are working). seperate the column TS pull apart dangling connector under the column and there should be continuity between the "in" wire from the brake light switch and the (2) "out" wires to the rear brake lights (with the stalk in neutral) this will elim or confirm the TS sw assy as the culprit ( www.mymopar.com will have the colors for you). Grab your VOM & this'll get you started. Holler when you can EDIT I missed Runners and Stumpys excellent advice

Update 4: replaced the turn signal flasher and the signals work well-strong and lights are bright both in dash and front and rear. Replaced emergency flasher, still have no emergency lights. Still have no parking lights or brake lights. Pulled brake light switch from pedal-put meter box to it (the connector w/ pink wires), have .06v going to it.
Checked fuses, these are the numbers:
instrument fuse-light switch off(measured from both ends of fuse)0.0/0.0vs; light switch on.01/.01
Taillight fuse-light switch off 11.5v (side of fuse closest to dash)/.07v (side of fuse closest to engine); light switch on 11.5v (side of fuse closest to dash)/.01v (side of fuse closest to engine)
Some questions asked: yes, front parking lights go out when headlights are on. Checked all connections to see if I pulled something lose-connections good. Agree, this is human error, just can't figure out where I went wrong; if I pulled a ground loose, IDK where it is. The space is barren where the master cylinder and braked pedal linkage is. Checked bulkhead connector in engine compartment and under dash-no loose wires or wires pulled loose. Even checked behind master cylinder to see if maybe I pinched wires between MC and body.
I started thinking voltage limiter got shorted, but then turn signals wouldn't (correct, I think).

there is a ground wire on the steering column which i think is down there. i just can't remember where. it has a crimped on rounded connector which is bolted to the column. i think it is for the horn though but i can't really remember. i also think the 4 ways run on the brake light circuit so make sure you didn't knock any of that loose.

Connected yellow wire (on brake light switch) to taillight fuse; side of fuse closest to dash, brake lights came on; connected to side of fuse closest to engine, no lights. Is it possible that the brake light switch is bad? When the problem first occurred I removed it from the bracket and sanded and cleaned it well to make sure I had a good ground there. Did I screw up the brake light switch pressing it back into the bracket?
I feel there is a pattern here, but it eludes me. While I've some got mechanical skill(enough to screw things up, as the saying goes), I recognize that my skills are "home schooled" through the trial and error process.
Your suggestions are giving me directions to go in, and I feel I'm getting closer to a solution.
Thanks again to all the replies!

mikemee1331- I've got that wire attached to the dashboard. Horn works. I will check 4 ways connections.

If I'm understanding your description of your voltage tests at the fuses, your brake light fuse is blown.

Fuses should have the same voltage on both ends, they aren't switches or loads.

Change some fuses. I bet you shorted the brake light wires while fooling around under the dash.

Also, don't the 4 ways get power through that same fuse?

Edit. Just saw your test with the jumper wire, you have confirmed a bad fuse. Basically you made your brake lights a test light.

Wanted to provide feedback on getting my lights to work again. While I had the fuse box removed from the dash, I cleaned it w/ electronic spray cleaner & put a soft wire brush to it. Ruederunner gave me the idea of the fuses; they were HF specials. I started field testing some of them & discovered they weren't passing all the current through. Went to NAPA, bought some real fuses & installed. While there, I purchased an electronic turn signal flasher & installed. Last, checked the bulkhead connector & found the one side got knocked loose on the master cylinder install-human interference on that one. Put power back on & the lights work; a little brighter & faster I might say.
Thanks again to the repliers for the items to check.

so the fuses had continuity but not enough flow? that one mighta thrown me; I'm glad it is all good now for you now