Tail light trouble

[BigPoser]

So in trying the get my truck road legal, I notice that my rear tail lights are working correctly and it's boggling my mind. I have already put a new headlight switch in the dash. Brake lights work. Blinkers work. Reverse lights work. Hazards work, but the dame running lights do not.

I don't get any power that I can tell from the rear harness or even at the firewall for that matter. Looking at wiring schematics has made my brain stop working properly and need some help on this.

Any insight is greatly appreciated.

Thanks in advance.

Brandon

 

[chengny]

How about rear side markers and license plate lights? I imagine they are not working as well - right?

But do you have brake lights and courtesy lighting. So the 16 orange circuit is hot. The tail lights branch circuit (16 orange 40 C) goes straight from the splice to the H/L switch. It goes through the H/L switch and comes out on the 18 brown 9 circuit.

After that it is a straight shot to the rear lighting group (tails, markers & plates).

You can ring it out starting at the H/L switch - if you get voltage on the brown wire there, move to the firewall and check on the cabin side. I see that you have already checked the engine side of the FW (I'm guessing) and found no voltage on that side.

So, if you are seeing 12 VDC at the H/L switch - on the brown wire - and nothing on the cabin side of the FW transit... Well, you've looked at the schematics as well as I did. We both know that if that's the case, the 18 BRN 9 wire must not have continuity from HL switch to FW transit.

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