No brake lamps, 1970 Fury.

[Carmine]

Just as background, when I power the brake lights directly through the turn signal contacts, they do light. I can't show you that on a video (easily), so take my word for it, or just believe the ammeter gauge as it moves to discharge.

OK boys, I need a shower. I expect an answer by the time I'm out.

 

[Davea Lux]

Just as background, when I power the brake lights directly through the turn signal contacts, they do light. I can't show you that on a video (easily), so take my word for it, or just believe the ammeter gauge as it moves to discharge.

OK boys, I need a shower. I expect an answer by the time I'm out.

Carmine:

Check your 4 way flasher switch to be sure it is properly parked,( ie turn it on and off). If it is stuck in the middle someplace your will have an open circuit to the brake lights. I assume you have already tried the obvious solution of bypassing the brake light switch to test its functionality.

Dave

 

[1966newport]

bad turn signal switch

 

[Carmine]

Carmine:

Check your 4 way flasher switch to be sure it is properly parked,( ie turn it on and off). If it is stuck in the middle someplace your will have an open circuit to the brake lights. I assume you have already tried the obvious solution of bypassing the brake light switch to test its functionality.

Dave

That's a good thought, and I'll make a point to move it around. However I have probably operated the flashers a half dozen times during this troubleshoot and they've always worked normally.

Regarding the removal of the brake switch from the circuit... Yes... that's what I'm doing when I jumper across the pink/white wires. Here's the circuit...

 

[Carmine]

Here is the first trouble shooting position, eliminating the brake switch and measuring voltage at white wire brass contact.

 

[Carmine]

Second position.

 

[Carmine]

Obviously my reluctance to replace the switch comes from the fact that they don't just hang on shelves at Autozone for $12.99. So I diagnosis the switch... If I didn't see 12v at the brass switch contact, I'd say the white wire is open somewhere (and should then spot the physical defect).

If the brake lamps didn't work when I apply 12v to the opposite side of the brass contacts (green/brown wires), I'd say those wires were open somewhere and go searching.

But the problem is, the only time the lights don't work is when I apply power using the white wire! WTF?!?

 

[Big_John]

If I'm reading this right, you are able to light one bulb at a time and not able to light both.. Correct?

 

[Carmine]

If I'm reading this right, you are able to light one bulb at a time and not able to light both.. Correct?

You are correct. I'm thinking about some kind of "load" issue where perhaps I don't have sufficient amperage from the white wire, but this gets beyond my basic electrical knowledge...

I would have to use a second jumper wire to run across the green/brown wires at the same time.

But keep in mind that my white wire will not even light ONE side, let alone both.

 

[Big_John]

You are correct. I'm thinking about some kind of "load" issue where perhaps I don't have sufficient amperage from the white wire, but this gets beyond my basic electrical knowledge...

I would have to use a second jumper wire to run across the green/brown wires at the same time.

But keep in mind that my white wire will not even light ONE side, let alone both.

OK, a couple things then.... My first thought was you had some sort of bad ground in one (or both) of the brake lights. That would sometimes allow one light at a time to light because it would find a ground path through the other bulb filament.

But since the white wire won't light either side, I'd say you have an issue with the white wire.

We always have to think current rather than voltage. The white wire passes enough current to show 12 volts but not enough current to light the light.

If the white wire is still passing through the connector, that's the first place I'd check. The other possibility is the wire got pinched somewhere along the line.

 

[Carmine]

OK, a couple things then.... My first thought was you had some sort of bad ground in one (or both) of the brake lights. That would sometimes allow one light at a time to light because it would find a ground path through the other bulb filament.

But since the white wire won't light either side, I'd say you have an issue with the white wire.

We always have to think current rather than voltage. The white wire passes enough current to show 12 volts but not enough current to light the light.

If the white wire is still passing through the connector, that's the first place I'd check. The other possibility is the wire got pinched somewhere along the line.

You have provided encouragement for me to press on. Perhaps going to church this morning will also help. The good news is, just connecting a new switch (without the labor of routing/installing it in the column) should also allow me to officially rule the switch in/out. I could pull one from one of my other hoopties, but I'd rather avoid that.

I think this switch should be the same from about 1970 (hazards on column) till perhaps as late as 1989, roughly the end of this steering column design in Mopars.. Anyone know for sure?

 

[Big_John]

If you really wanted to diagnose the white wire, you could do a voltage drop test across it. That would tell you for certain that is the issue.

My favorite video on the subject, but it confuses some because he shows the example (as most do) in a "no start" type problem.



You could bypass the switch with a jumper wire across the switch to the connections on the pink wire and white wire instead of replacing the switch.

 

[Carmine]

Well Big John, you win the prize... I was starting to remember some of what I learned about voltage drops back in HS electronics class and your video jogged my memory. I traced through the circuit looking for the point of resistance... The obvious one was a crimp that was done when someone (not me, so this was before I bought it back) replaced the TS canceling cam. So I soldered it and got all excited to see my brake lights glow... And was crushed by failure.

At that point I cobbled together a switch I saved with a bad canceling cam and re-soldered the other cam. That fixed it, although what a b*%^h! Oh well, I replaced the ignition key lamp while I had the column apart, so somebody benefits from that when it goes on ebay!

I never did find a compromised wire... Pried apart the hazard switch and it looked OK as well. At least I refreshed that knowledge and fixed it. I shudder to think what this would have cost at a shop!