No brake light/taillight on driver’s side, everything else works

Are you sure the bulb socket for that nob-working side is good? Get that multimeter yet? The schematic shows a "dot" where the two rear lights or "tail lights" are split, each side having +12 Vdc being routed to the left and right combination light assemblies. If the passenger side tail light assembly works correctly, then all the circuitry from that "split", the dot, back to the battery is working as designed. Since the driver's side combination light, the tail light, is not getting +12 Vdc then you have to find where this splice is located. Is it right there by the bulb socket? Looks like two GREEN wires are spliced together. If finding the factory harness connection is to hard, you could just make your own power "splice" by tapping into the working tail light green wire at the back of the plastic light assembly and routing this new wire over to the non-working tail light assembly. Use green wire.

 

Not a broken wire, it’s spliced into the harness, just a little of that white whispy tree seed stuff that sometimes floats in the air

 

I did get the multimeter in, it’s only getting ~9.8 volts on the driver’s side where the pass side is 11.6

the pins on the connector are the same orientation so I swapped taillights, results didn’t change (driver’s side running light still out)

 

I had this same symptom and my issue turned out to be damage to that wire after the splice which split off to the passenger side. I was not getting any voltage at the connector though so YMMV.

 

So, the green wire coming into the driver's side (defective side) combination light, from the harness, is a single non-spliced green wire? That single green wire (at the empty socket) is only showing +9.8 Vdc to chassis ground? Hard to believe the factory schematic then. There has to be some voodoo wiring connected to to your driver's side tail light harness, that is not connected to the passenger's side. If it were mine, I would snip the green wire back a several inches to remove the harness wire and let it hang. Then splice in another +12 Vdc power feed from the passengers side green wire to verify that both lights work correctly when the tail lights are turned on from the combination switch. If all is good, then start the process of finding the voodoo that has been connected to your factory wiring harness, which is dragging the battery voltage down to 9.8. Even at +9.8 Vdc, the bulb should glow dimly I would think. Got a good/solid ground connection for that bulb (tail light portion of the bulb)? The other bulbs in that assembly all work normally?

 

So where is that splice located physically????

 

My understanding is this is for 2000 and older, in 2001 they updated to the wiring to run from one taillight harness to the other.

There are two splices, one near the shock and the other near the bumper where the harness splits off to the passenger side. The first splice sends one green wire directly to the right running light and another down to the second splice; the second splice has three wires, one to each license plate light and one to the left running light.

 

Whoa....that bundle of green is in need of some TLC. Looks like Coldaccord has a fun task ahead tracing the voodoo that is sucking the voltage away from his driver's side taillight bulb. Sounds like a funky ground connection.

 

^but it shares the ground with the working brake light

I took the easy route and just ran a jumper from the other side.

 

OK then......all works correctly now. The slice point has to be the failure spot.