Here is what I know
The bulb is good.
I have 12 volts on the R/Y side
The RLU isnt pulling the ground down to light the bulb.
Is this a common failure of the RLU?
I found an interesting thread on removing/bypassing the RLU. That idea deserves some thought.
When my starter switch needed cleaning, that particular device didn't tell me that my light was out anyway!