All the reasons why the new brake light harness won't work?

[gran coupe john]

Have the wiring diagram. Check most everything. Still no go. Any suggestions would help. Maybe overlooked somethi

 

[Challenger RTA]

Not sure what your question is about. Brake light on and won't go off when parking brake is released? Brake light is on for system failed? The wring harness doesn't fit?

 

[gran coupe john]

Can't get any power to the brake lights.

 

[Challenger RTA]

Can't get any power to the brake lights.

Rear brake lights?

 

[Challenger RTA]

Look at the colored diagram I posted. Unplug the connector under the column.

Check if you have power to the EMG Flasher and Turn signal Flasher. Use one of those powers to jump to each connector. You may see a small arc. The horn needs ground .touch to ground.You will here it. Then touch to each connector as someone watches would be a help. This way you will know if everything else is in order

Everything goes through the TS switch , pink to the brake switch , white up the column to the switch , then 4 wires out to the 4 corner lights the brake lights should activate the 2 wires at the rear & interupt with signals , , 2 wires for each turn signal L&R , and all 4 wires with hazard lights .
If you short the 2 wires at the brake switch the white wire up the column should be powered

Short cut. Unplug the wires from brake sw. Put a jumper in see if they work.

 

[Challenger RTA]

This is the plug under the column.

This diagram is an in general diagram for pin out connection. Not for wire color code. Don not follow. Could be GM Ford or other.

 

[Challenger RTA]

Check the plug in the drivers kick panel might be loose. maybe a ground.
Also you can apply power to all the wires except the dark blue. That is for the fuel gauge.

 

[gran coupe john]

Yes the rear brake lights. I will give it a try.

 

[Ronbo73]

When troubleshooting always split the problem in two so that you can rule out one or the other, ie unplug the rear lamp harness in the drivers kick panel and check that half first. Make sure the rear lamp harness has a good ground. My 73 has the ground wire near the drivers side taillight. Remove the drivers side kick panel and disconnect the rear tail light harness plug. With a battery or 12Vdc power supply, connect ground to a know good ground source then 12Vdc to one wire at a time and see if that light illuminates. Do each wire except the dark blue, like Challenger RTA stated. That is how I knew that my rear lamp harness was good and then I could look elsewhere.

Also make sure that each connector in the plug, both sides, are seated all the way in to the plug. Sometimes they push out when the plugs are put together. If not seated correctly within the plug itself you will not have a good connection.

Make sure you a good ground, that is most important. Clean all paint away from the backside of the connector and use some dielectric grease to keep moisture and rust out.

 

[gran coupe john]

Thanks, I now believe it is not grounded correctly. Didn't see a ground wire on the wiring harness. ( CAR HAS BEEN DISASSEMBLED FOR 8 YEARS) Getting so close to the finish, can taste it.

 

[moparleo]

The bulb socket that snaps into the taillight housings are the ground. You should add at least a couple of ground wires to the bulb sockets and just use a sheet metal screw into the body brackets somewhere.
Number one cause of harness problems is the grounds.
Also perfect time to install some quality bulbs.
No China or Asian bulbs.
I use quality Nickel plated European made bulbs.
No corrosion like copper/brass housing bulbs.
This is what companies like BMW use. Long life, no ground issues.
Phillips make several.
And lastly, the turn signal switch powers the brake light circuit. So a good place to look.
Remove the steering wheel and check the switch, Pretty fragile unfortunately.

 

[Challenger RTA]

Didn't see a ground wire on the wiring harness.

Sometimes you see them sometimes you don't. I don't know if it was a been counter decision or it was realized grounds are a good thing to complete a circuit.

 

[gran coupe john]

Got a whole bunch of nos bulbs from the 70s. Father had a shop back in the day. I take my Sundays off, and away from the coupe. Monday is the day I will get the brake lights working? Thanks for all the great information.

 

[moparleo]

Check your 40+ year old NOS bulbs.
They are really good for a nut and bolt OEM restoration, but newly manufactured bulbs have been improved over the years and have improved materials and bulb life.

 

[gran coupe john]

It definitely was the ground!! Thanks for the help you all. Now I got a bad dimmer switch, and flasher. Looking for a place to get them quickly.