Another blinker brake light question

[geosar]

I have scoured the site and apologize if this is redundant redundant.
1972 Ford bronco. Original wiring. The front blinkers work. The rear passenger side blinker and brake light work. All running lights work. All fuses intact.

The front driver side blinker works. The rear blinker and brake light do not work. New two-wire connector for the rear blinker/brake light, fresh ground at the left rear light assembly. The bulb works when powered by a separate 12 volt source.

So what is next? 1) hand over hand follow the wire to the front? I believe the left blinker and brake wire is green. 2) disconnect the blinker wire connector under the dash and apply power to the left blinker post? 3) Check the blinker switch at the steering wheel somehow ?

I dunno. Thank you for any help. I am missing something.

George
Arizona

 

[serial car restorer]

2) disconnect the blinker wire connector under the dash and apply power to the left blinker post?

This should be the first test. If it works, you probably have a bad turn signal switch.

I believe the left blinker and brake wire is green.

Green out of the TS switch should be the right side. Left should be yellow/black.

 

[geosar]

Yellow black You are correct. Thank you And thank you for the excellent wire schematic.

George

 

[Speedrdr]

After the muffler shop set the underside of my previous EB on fire, I had to do the hand over hand method to find/reconnect all the D/S wires from the seat back. It was a PITA but kind of gratifying to learn how the circuit was run and as a bonus I got lights connected correctly and back up lights for the first time.

 

[Oldtimer]

A couple of possibilities:

1) Connector C-43 (shown in Arne's post) may be dirty/corroded.

On my 68, it is located above frame near driver side axle bump stop.

2) In the past 1/2 century someone may have towed a trailer with your Bronco.
The goto connector for trailer light hookups is a Scotchlok connector.

These are the worst connector ever invented (and if I were King for a day, they would all be burned).
They slice the insulation and a few strands of the wire, weakening it, and allow moisture to turn copper wire into a big green ball of electron blocking mayhem. Then at some point the trailer wires and connector are removed.
The only way to the find slices in the insulation is hand over hand.
Fortunately the lazy people that use these connectors, are lazy, so the splices are probably close to the back left corner of the undercarriage.

 

[Brush Hog]

Are the tail light buckets/wiring all new? When i installed new ones a year or two ago I couldn’t get them to work. Finally found one post mentioning some new buckets were wired backwards from the manufacturer. I swapped the wires and it fixed the problem.

 

[geosar]

A couple of possibilities:

1) Connector C-43 (shown in Arne's post) may be dirty/corroded.

View attachment 947346

On my 68, it is located above frame near driver side axle bump stop.

View attachment 947348

2) In the past 1/2 century someone may have towed a trailer with your Bronco.
The goto connector for trailer light hookups is a Scotchlok connector.

View attachment 947345

These are the worst connector ever invented (and if I were King for a day, they would all be burned).
They slice the insulation and a few strands of the wire, weakening it, and allow moisture to turn copper wire into a big green ball of electron blocking mayhem. Then at some point the trailer wires and connector are removed.
The only way to the find slices in the insulation is hand over hand.
Fortunately the lazy people that use these connectors, are lazy, so the splices are probably close to the back left corner of the undercarriage.

Thank you. I received the car today and will start using my flashlight and investigate all of the suggestions. I appreciate you help. I did not appreciate the under the car connector in addition to the under the dash connector. Thank you
George

 

[geosar]

So, after gentle persuasion the plug under the dash came apart. I have continuity from the blinker/brake to the yellow-black connector to the distal part of the plug. I have a black square plug not the horseshoe gray style.

It turns out that the car is electrically dead when that big plug is separated so I will have to use a needle in the connections to determine who is getting power from the turn signal switch.

Thank you so far for all of the help. I assume the large yellow wire is a main power connection for the car in general similar to the heavy wire I discovered in the gauge cluster. I do not see a 12 or 14 gauge yellow wire going though the plug for the turn signal switch under the dash.

Onward. So far so good. Now to learn how to remove the steering wheel without breaking anything. Doing well so far.

George

 

[geosar]

I finally dove into the wires leading from the dash to the left rear turn signal. I checked continuity starting from the taillight. I finally found a rat chewed wire bundle near the firewall in a very difficult area to reach. (Should have started from the engine compartment and saved some time.) So tomorrow I will repair the broken wires and be thankful I may not have to disassemble the steering wheel.

Thank you for the help

George
Arizona