Ok, first off, UNPLUG the head-light. That's your main drain on the battery while you're figuring out your tail-light. Because, as ace mentioned ,you have to do all of this with the ignition ON. It would suck to have to jump it later, after you get this figured out.

That said, Use the multi-meter first to check all of the fuses. First set it to continuity-check. Pull each fuse, put one probe on each leg of the fuse, it will either beap or OL
(over-load) read-out, this means the fuse is good (a complete circuit). Replace that one and go to the next. Check all of the fuses, so you don't mistake which one is correct.

Next, pull the buld from the tail-light, use the multi-meter to check the bulb. The
base of the bulb should be brass cap with 2 contacts sticking out of the base insulator.
Hold one probe to the brass cap and one to the tip of each contact, in turn.
Same thing, beep is good, no beep is bad. Looking at a fuse or bulb is no guarentee.
They can break connection where you can't see it.

After that, you'll know if the bulb/fuses are good and that the problem lies elsewhere.

Check that out first. If it's deeper than fuse/bulb and you don't know theory, it's gonna take a bit of research on your part, or I'm gonna be posting a novel sized flow chart.
If you're sure it's not bulbs post back and I'll tell you how to start testing or find some good references for you.

Ern

 

Here ya go, cbrf links and a thread for diagrams on the F4

Cbrf f4 diagrams

 

I haven't replaced the bulbs, no filament is broken in either bulb. Could it make a difference?

 

Replacing your bulbs would be the first thing to do when you make an expense list.. Since they will prob cost the least

 

+1 to ace's last comment.

Visually intact filaments doesn't mean the bulb is good. That's why I
suggested testing it for continuity. The connection can break in the base, where you can't actually see it.

For $2, replacing it and seeing if that works, is a cheap diagnostic. Even if it's not
the solution, you're only out $2 and you have a spare for later.

Ern

 

what is the bulb number? i need to replace one of mine also

 

check inside the little case that your light switches are on i had this same thing happen to mine and it was bad solder inside the switch, i resoldered the wire and they instantly came back on... dunno if it helped but it might