Rear lighting

[Square AL]

Alright guys, first time asking for help. I see plenty of threads related to rear harness lighting troubles, but I can’t pinpoint the issue. I’ll post what’s going on and then list what I’ve done, feels like I’ve covered everything but I’m missing something. It’s only the rear end, front is good.
Symptom:
Passenger side brakes and blinkers dim, won’t light up second filament in bulb
No reverse lights or license plate lights.
Both Rear tails and runners-good
Driver side brakes and blinkers-good

Remedies:
Column switch engages appropriately
Flashers engage all bulbs (passenger side rear dim)
Fuses and relays-good
Tested bulb sockets-good
Tested/changed bulbs-good, and yup I’ve got the bulbs installed correctly in the socket
Grounds-good even added a couple more
Voltage good at bulkhead.
I’ve added an illustrated diagram for reference. Imma head out and check the brown and dark green in the rear harness for breaks in the meantime. Any ideas are welcomed, Thanks in advance guys!

 

[Ricko1966]

Grab an incandescent test light.*(not led not a meter) preferably a milton I think those use a #89 bulb. Give it a good ground, then start pulling light bulbs probe the connectors that touch the contacts on the bottom of the bulb. Note any connection that doesn't make your test light work properly. Reason for an incandescent bulb is an led or meter has such a low current draw,things that appear good an a meter or LED actually don't have sufficient current. If all functions work using an incandescent as a probe,you have a bad ground, sometimes the sockets themselves don't ground to the bulbs. Post your findings. Edit,looks like everything is LED now all I could find incandescant was toolaid 27000 I've always been happy with the toolaid tools I bought. I'm going to but one just to have it,before they go LED also.

 

[AuroraGirl]

Alright guys, first time asking for help. I see plenty of threads related to rear harness lighting troubles, but I can’t pinpoint the issue. I’ll post what’s going on and then list what I’ve done, feels like I’ve covered everything but I’m missing something. It’s only the rear end, front is good.
Symptom:
Passenger side brakes and blinkers dim, won’t light up second filament in bulb
No reverse lights or license plate lights.
Both Rear tails and runners-good
Driver side brakes and blinkers-good

Remedies:
Column switch engages appropriately
Flashers engage all bulbs (passenger side rear dim)
Fuses and relays-good
Tested bulb sockets-good
Tested/changed bulbs-good, and yup I’ve got the bulbs installed correctly in the socket
Grounds-good even added a couple more
Voltage good at bulkhead.
I’ve added an illustrated diagram for reference. Imma head out and check the brown and dark green in the rear harness for breaks in the meantime. Any ideas are welcomed, Thanks in advance guys!

where did you put all your grounds, the bed? do you have the body and frame to the battery sufficiently grounded? The frame to battery ground is a very weak ground and the chassis to the battery can be too