^Totally understood.  Thank you Steve, for all your tireless advice and efforts.

Chased a couple of rabbit trails over the weekend:

• Discovered I had installed the left side of the dash incorrectly (the dash frame was under the bracket instead of resting on it, and this was pinching the 3 wires to the horn relay).  Given that my horn doesn't work either, I thought maybe there was some overlap b/t the horn and parking light circuits and maaaaybe the horn circuit grounded out on the dash bracket, but...  No change even after I got everything straightened out.
• I tried the OEM (tube-type fuses) fusebox to see if something was amiss in the newer MSA blade fuse box.  No change.

At this point, the plan is to move on to some other needs to try to rebuild some momentum/positive vibes before I try to tackle this thread's issue again.  Discouraging.

Have you checked all the grounds? Among others, I am pretty sure there is a ground under the car in the area of the right tail light. I have found loose grounds will make for some weird electrical issues. 

Been on an overseas trip for the better part of the last month (France!).  Just now getting back into this...

On 5/23/2022 at 10:02 AM, emccallum said:

Have you checked all the grounds? Among others, I am pretty sure there is a ground under the car in the area of the right tail light. I have found loose grounds will make for some weird electrical issues. 

Supposedly there's a ground on the chassis rail near where the filler neck comes into tank.  I can't see any evidence that one ever existed (no screw hole, stud, nothing) and no ring terminal on the harness either.

No evidence of a ground near the antenna mount, either.

 

 

HOWEVER:  Some progress, maybe?

I unplugged all 4 side marker lights, and........the dash lights, front (under bumper) markers and taillights came on when the combo switch was turned to the middle position!  And fuse stayed intact!

Brake lights and turn signals are still inop, but it was FANTASTIC to see that pale green glow from the dash lights.

Gonna try to plug in the side markers one at a time and see if I can isolate (that part of) the problem.

I am not 100% positive but very, very sure the first picture is the bolt that holds the ground in the right rear corner of the car. 

The second picture is the wire harness that goes from the right rear taillight area to the fuel sender unit. It has the ground wire.

 

 

^That 1st pic jogged my memory.  I did get that ground bolted down before I reinstalled the tank.  See:

https://www.classiczcars.com/forums/topic/63478-routing-for-fuel-level-sender-harness/#comment-592045

You love to see it...

(I promise the rest of the tach lighting is on—just didn't come through in the pic—as are the 3 dash-top gauge lights)

So plugged in the 4 side markers one at a time and checked the circuit after each.  As near as I can tell, I plugged in the front left side marker wires backward.  The engine bay was blacked out at some point in the car's past (it's not any more) and the wiring harness—and its wire colors—painted over, including the wires to the side markers.  I just hadn't done a good enough job of matching black to black and green to green the first time around.

So that's done.  Still no brake lights though, and while the turn signals work on the right side, only the front left works.  I've checked and re-checked the wiring; will keep at it tomorrow.  Just wanted to share progress and a couple of pics.

Making progress!

More progress:  All 4 turn signals work now!

I had to clean out the switch twice (it's spotless inside now) to get them to work.

Horn works also after cleaning and re-lubing the contact ring on the back side of the steering wheel hub.

Only thing left are brake lights, and we're 100% operational...

Today's developments:

Using the below as a reference (thanks so much Steve!) I checked the continuity of each taillight-related wire from connector to connector:

Continuity was good between everything EXCEPT for the below:

I ran a wire between the connections and the brake lights came on when I pressed the pedal!  However—when I tried the turn signals, both lit up when I turned to the left, and the right one illuminated (correctly) when I turned to the right.

I pushed the car back in the garage and the jumper wire fell out.  I tried the brake pedal again and the right one came on anyway (???).  Both turn signals worked OK.  But then I tried the brake pedal again and got nothing.

This is such a moving target.  There's clearly a marginal connection or broken wire somewhere.  Going to pop out the hazard switch next and inspect it.  The turn signal switch is immaculate inside and I have no reason to doubt it.

I feel like I'm working on something with Lucas electrics at this point...

If you're getting one brake light to work, but not the other, things to consider:

1. It's still the turn signal switch. Sometimes the tabs are not bent at the correct angle to make contact.
2. Bad/wrong bulb
3. Wiring issues

You should try to check the voltage at the white/red (right) and white/black (left) wires at the 6 pin connector at the steering column. I suggest using a t-pin to allow you to monitor the voltage with the connector put together.

Stick the t-pin into the back side of the connector, and touch the positive probe of your voltmeter to the t-pin and the negative probe to a good ground. Step on the brakes to see if you have voltage. 

You can also see if you have continuity between the green/yellow wire at that connector to both the white/red and white/black wires.

If either of those tests fail, your turn signal switch may need to be tweaked to adjust the contacts.

1. I've had the turn signal switch apart 4 times now, and I tried bending the tabs slightly a couple of different ways.  No difference.  It's spotlessly clean inside also.  Not sure what else to do there.

2. The bulbs are the same as they were before the restoration.  1157LL I believe...

3. So after cleaning out the hazard switch and getting it plugged back in, the right taillight works, and the turn signals works BUT ONLY when I physically move the 2 connectors coming out of the back of the hazard switch a certain way with my hand.  I really think there's a break or a short in the dash wiring somewhere.  I'll perform the above test, but I really think the dash is going to have to come out again.

Thanks as always for the input, Steve.

Edited June 27, 20222 yr by BoldUlysses

25 minutes later, and...

Dash is out.  (sorry about the mess)

Going to flip it over tomorrow and see what's what.  Will report back.

By the way Steve, I performed the test you recommended:

• 12V between white-black and ground.
• <1V between white-red and ground.
• Continuity between both green-yellow and white-red and white-black on the back of the switch.