66 bronco steering column wires

[Rdtrip]

I have a list of wires coming from the steering column. They do not match colors with the JBG harness. I have no original wires to compare to. I have to sort out what is what, and I need some guidance.

Column wire colors:
green
blue
green/white
green/orange
orange/blue
white/blue
yellow (larger wire)
blue/yellow (larger wire)

Connections from new harness:
Harness to column colors:
Small pigtail = yellow and green
Large pigtail = yellow, green, blue, blue/yellow, green/white, white/blue

So at the moment, with ALL NEW wiring harnesses, I have hi beams, no low beams. I have parking lights in front which turn off when headlights are on, but work as they should when just running lights are on. I have a left tail light, no brake lights either side. Manual brakes and single master cylinder with switch. 3 on the tree also. Hazards wired as factory called for, they work in front only. Heater controls work good, new headlight switch as well as all the other switches on the dash. Old original steering column and loose column wires, no block at end of wires to complete pigtail assembly or compare. I made my own tail light harness for the cab back, wired to the "correct" pigtails in the new harness. I only have power for the left side circuit, no power at all for the right side. Electrical is my weak spot, so any help is appreciated...thanks in advance Viperwolf1

 

[Oldtimer]

I am assuming you bought the "Under Dash Wiring Harness 1966" from JBG?
Did it come with any documentation?

​

Connections from new harness:
Small pigtail = yellow and green
Large pigtail = yellow, green, blue, blue/yellow, green/white, white/blue

I would check each of these wires with a test lamp.
One will have 12v all the time, from headlight switch to power horn
One will have 12v when brake pedal depressed
One will have intermittent 12v, from flasher with key ON (may need more bulbs to get it to blink)
The remaining 5 wires with 12v applied to them with a jumper should power:

• Horn
• Right rear brake lamp
• Left rear brake lamp
• Right front turn lamp and cluster right turn bulb
• Left front turn lamp and cluster left turn bulb

So with ALL NEW wiring harnesses, I have hi beams, no low beams.

Power is making it from headlight switch to dimmer switch, to hi beam bulbs, check dimmer switch, connector, continuity of RD/BK stripe wire (low beam) from connector, thru bulk head connector, to each headlight socket.

I have parking lights in front which turn off when headlights are on, but work as they should when just running lights are on.

This was normal for 66. First click of headlight switch is Parking lamps (front and rear), Second click is Headlights with Running lamps (rear only).

I have a left tail light, no brake lights either side.

No brake lights till turn signal switch connected.

Hazards wired as factory called for, they work in front only.

No rear hazard lights till turn signal connected.

Old original steering column and loose column wires, no block at end of wires to complete pigtail assembly or compare.

See attached drawings for my WAG at wire color inter-connects.

I made my own tail light harness for the cab back, wired to the "correct" pigtails in the new harness.
I only have power for the left side circuit, no power at all for the right side.

Brown wire is running lamp circuit. Check where Brown wire splits to left & right side in tail light harness.

See attached PDF of 67 schematic by @SeaBiscuit68.

 

[Rdtrip]

I am assuming you bought the "Under Dash Wiring Harness 1966" from JBG?
Did it come with any documentation?

View attachment 954790​

I would check each of these wires with a test lamp.
One will have 12v all the time, from headlight switch to power horn
One will have 12v when brake pedal depressed
One will have intermittent 12v, from flasher with key ON (may need more bulbs to get it to blink)
The remaining 5 wires with 12v applied to them with a jumper should power:

• Horn
• Right rear brake lamp
• Left rear brake lamp
• Right front turn lamp and cluster right turn bulb
• Left front turn lamp and cluster left turn bulb

Power is making it from headlight switch to dimmer switch, to hi beam bulbs, check dimmer switch, connector, continuity of RD/BK stripe wire (low beam) from connector, thru bulk head connector, to each headlight socket.

This was normal for 66. First click of headlight switch is Parking lamps (front and rear), Second click is Headlights with Running lamps (rear only).

No brake lights till turn signal switch connected.

No rear hazard lights till turn signal connected.

See attached drawings for my WAG at wire color inter-connects.

Brown wire is running lamp circuit. Check where Brown wire splits to left & right side in tail light harness.
View attachment 954800

View attachment 954801

See attached PDF of 67 schematic by @SeaBiscuit68.

It did come with the schematic, for each harness. Again, electrical is not my strong suit. I have full power on the yellow wire, with key and headlight switch off. I have red/black wire with power after depression of brake pedal. When I have the hazards on I get blinking power on white/blue stripe, green/white stripe, and green/yellow stripe. I have power to larger light blue wire with key on but nothing with key off.

 

[Rdtrip]

It did come with the schematic, for each harness. Again, electrical is not my strong suit. I have full power on the yellow wire, with key and headlight switch off. I have red/black wire with power after depression of brake pedal. When I have the hazards on I get blinking power on white/blue stripe, green/white stripe, and green/yellow stripe. I have power to larger light blue wire with key on but nothing with key off.

I have to grab a power probe..

 

[Oldtimer]

I have power to larger light blue wire with key on but nothing with key off.

With key ON, pull the turn signal flasher, and power to larger light blue wire should stop.
If so this is the turn signal blinker source, and it won't flash till there are some lamps connected to it.

This is a corrected schematic for my WAG at wire color inter-connects.

I have full power on the yellow wire, with key and headlight switch off.
I have red/black wire with power after depression of brake pedal.
When I have the hazards on I get blinking power on white/blue stripe, green/white stripe, and green/yellow stripe.
I have power to larger light blue wire with key on but nothing with key off.

Your original post has NO mention of red/black or green/yellow stripe wires.
In FACTORY harness RD/BK wire is 12v from brake light switch to turn signal switch,
and GN/Y is 12v from fuse panel (dome & cigar) to head light switch.

Column wire colors:
green
blue
green/white
green/orange
orange/blue
white/blue
yellow (larger wire)
blue/yellow (larger wire)

Connections from new harness:
Harness to column colors:
Small pigtail = yellow and
green
Large pigtail = yellow,
green,
blue,
blue/yellow,
green/white,
white/blue

 

[Rdtrip]

Ok, so I've tried to sort this out. My red/black wire comes from the hazard flasher harness and goes to the green wire, and green/yellow goes to green/white. That's going INTO the JBG harness. By the way, nowhere in the instructions does it say which wire connects to which only states wire number/colors and minimal connections. None state hazard flasher harness to JBG harness, non show any colors of wires, and nothing from the factory turn signal switch to the harness. That's my main issue, getting the correct wires from my turn signal switch/column to the main harness correctly. The colors on the turn signal switch are faded and barely readable, but these are the wires I'm trying to get connected. Ugghhh

 

[Rdtrip]

Ok. So, after checking and power probing my wiring, I now have left and right turn signals front and rear, taillight on left, parking lights up front, high beam headlights, brake lights, hazards. I do NOT have low beam headlights or a right rear tail light. Everything else is working as it should. All other electrical works fine. Where to go from here to find low beams? I have power at the dimmer switch for low beams, just not to the headlights. I have no power for the harness going to the right taillight either, which to me is odd since I have brake and turn on the right... All bulbs are new, tested and functioning great. I have swapped left to right the harness for the taillights and one does work, but same deal. One works, one doesn't on the taillights. Anyone have an idea how to make the right tail and low beams work? I appreciate the help and advice. Thanks

 

[Rdtrip]

I just tested the pigtail at the headlights. I have power to both the red/black wires AND the green/black wires at the same time on high beams, no power on low beams. New headlight switch, new dimmer switch, new headlight bulbs, new complete harnesses throughout the 66. I'm confused by this one...

 

[Viperwolf1]

The only way you could have power to both red/green and red/black wires is if one or both of your headlight grounds wasn't connected.

 

[Oldtimer]

Head light dimmer switch.
Power comes from headlight switch to dimmer switch, RD/YL wire.
The RD/YL wire connects to the MIDDLE contact on dimmer switch.
VERIFY this.
The dimmer switch flip flops output to SIDE contacts on switch.
The RD/BK wire is LOW beam.
The GN/BK wire is HIGH beam.
If the ground connection on either headlamp is bad power will back feed to other headlamp, thru the filaments in the bulbs, and it is hard to tell if both filaments in both lamps are working properly.
Disconnect one lamp and check low and high beam filamants in other lamp.
Re-connect 1st lamp, disconnect 2nd lamp and check high beam filamants in 1st lamp.
Re-connect 2nd lamp.
If you have low & high on one of them, check ground connectio for other lamp.
Still no low beam, disconnect harness from dimmer switch.
Jumper 12v+ to the side contacts of harness and check head lamps.
If no low beam, trace RD/BK wire from dimmer switch, thru fire wall, and out to both headlamps.

 

[Oldtimer]

I have swapped left to right the harness for the taillights and one does work, but same deal. One works, one doesn't on the taillights. Anyone have an idea how to make the right tail and low beams work? I appreciate the help and advice. Thanks

How are you swapping left & right harness for tail lights?
Probe the harness connector at the right tail lamp. Do you have running lamp power when headlight switch is on?

 

[Rdtrip]

How are you swapping left & right harness for tail lights?
Probe the harness connector at the right tail lamp. Do you have running lamp power when headlight switch is on?

I have 2 pigtails on the dash harness specifically for the left and right taillight wiring, as per the harnesses I bought from JBG.

 

[Rdtrip]

Head light dimmer switch.
Power comes from headlight switch to dimmer switch, RD/YL wire.
The RD/YL wire connects to the MIDDLE contact on dimmer switch.
VERIFY this.
The dimmer switch flip flops output to SIDE contacts on switch.
The RD/BK wire is LOW beam.
The GN/BK wire is HIGH beam.
If the ground connection on either headlamp is bad power will back feed to other headlamp, thru the filaments in the bulbs, and it is hard to tell if both filaments in both lamps are working properly.
Disconnect one lamp and check low and high beam filamants in other lamp.
Re-connect 1st lamp, disconnect 2nd lamp and check high beam filamants in 1st lamp.
Re-connect 2nd lamp.
If you have low & high on one of them, check ground connectio for other lamp.
Still no low beam, disconnect harness from dimmer switch.
Jumper 12v+ to the side contacts of harness and check head lamps.
If no low beam, trace RD/BK wire from dimmer switch, thru fire wall, and out to both headlamps.

View attachment 955404

View attachment 955405

Thank you for the great explanation. That helps a lot. I will check this Friday and see what I find. Thanks again

 

[Oldtimer]

I have 2 pigtails on the dash harness specifically for the left and right taillight wiring, as per the harnesses I bought from JBG.

When you swap harness connections at the dash, right side running lamp never works?
Need to check right side harness end to end for broken wire or connector contact.

 

[Rdtrip]

Right side works when swapped over from left. Bulb and socket clean and good, well grounded. It's something with the main harness I believe. I'm going back into it on Friday and see what else I can find. Thank you

 

[Rdtrip]

The only way you could have power to both red/green and red/black wires is if one or both of your headlight grounds wasn't connected.

I have both black wires grounded to bare metal at the core support. So, since they are both grounded, why do I have both red/black and green/black with power on the high beam setting of the dimmer? I have no power on low beam setting at the headlights but I do have power at the low beam setting on the dimmer. This is a brand new body so rusty or corrosion is not a problem. All electrical has been replaced with brand new aftermarket stuff, and none of it is pinched, folded crimped, damaged at all. I'm inclined to think my new dimmer or harness for it are made incorrectly. I'll probe into that Friday.

 

[Rdtrip]

Verified dimmer functionality. Center is power, red/yellow. Green/black is high beam, they both work. Red/black for low beam have no power going from dimmer to headlights either side. H6024xv headlights, verified pin position per Sylvania description. Still no right side tail light. I have only high beams, no low beams. Everything else works exactly as it should including heater functions, turn signals and hazards. Steering column wires are good and correct now. Still stumped on the low beam circuit so I'm unwrapping the harness now to chase it down further. Thanks for the help guys!

 

[Rdtrip]

Haha! Got the low beams figured out! The red/black wire at the headlight pigtail had power through the harness, and stopped power supply right there. I clipped the connector, tied the wires back together after testing for power and there it is! So the wire connection didn't appear to be stripped correctly and the insulation was trapping the wires from making proper contact. I now have high beams and low beams, but still no right side tail light. That's next..lol