[steinklatre]

In summary, wiring up the tail lights with a painless wiring kit for the 72 with the four lights, interior two being for reverse only.

Observation 1
If I disconnect the brake switch I have 0 volts at the (left turn, right turn, taillights, and brake lights) regardless of the position of the light switch.

Observation 2
With the brake switch being wired up the rear lights wiring all have a constant 12 volts (left turn, right turn, taillights, and brake lights) regardless of the position of the light switch.

Observation 3
With the brake switch wired up and touching (left turn, right turn, taillights, and/or brake lights) wire to the bumper causes the light (whichever wire it is for) to turn on.

Observation 4
Turning on the hazards on the column I have cannot hear the relay coming on and off.

Notes

• I have a Dakota Digital gauge cluster but I think that doesn't matter in this case
• I ran a common ground wire from the fusebox to the rear tail lights vs putting a grounding screw in the trunk.

Tests Conducted

• Tested the brake switch with continuity on multimeter => passed
• Tested the flasher relay with 12 volts and shorting to ground on the bench and I could hear the relay closing => passed
• Tested the light switch with a multimeter and everything had voltage, where it was supposed to on the connector => passed

I am scratching my head with what the issue is so any idea is a good idea!

 

[smitty454]

Did you swap out the bulbs in the taillights? The reverse lights and the brake lights are two different types of bulbs and will cause this issue if you get them mixed up.

 

[steinklatre]

Did you swap out the bulbs in the taillights? The reverse lights and the brake lights are two different types of bulbs and will cause this issue if you get them mixed up.

I just went and took a look at the bulb housings to verify and those are correct, I will verify the wiring this evening.

 

[steinklatre]

Got it all sorted today. Didn't realize how the brake switch worked so was fighting that and had a missing fuse for the tail lights so once I stopped and thought it came together nicely.