I have an 85 which didn't come with the SR5 instrument cluster. I found an 86 at a local salvage yard with all the goodies mine never had.
I have an 85 factory service manual which details both gauge clusters on pages BE-22 and BE-23.

So here's my problem which I hope you all can help me with:

I found a wire on the 86 cluster in pinout location C10 which is not shown in my factory service manual. This wire is not on the existing wiring harness of my truck either. It is a yellow wire with a blue stripe (most likely, it is designated Y-L in the Toyota wiring diagrams) and after looking at the back of the original cluster it was attached to, I see it connects to a low fuel warning indicator light.

I can find no reference of this wire in my service manual. If someone here has a factory service manual for an 86, would you please locate this wire and tell me where the heck the other end hooks up to?
I'd like to utilize this option. The dealer wasn't much help and I've found very little info about this light on the Toyota forums and the internet in general.

Thanks much for any help you all can shed on this mystery to me!

I didn't check a wiring diagram, but I assume it would connect to the low fuel sender at the tank. Your truck likely doesn't have one.

Dave