Take the light panel off the wiring harness... and measure the voltage at
the wiring harness... I suspect that the taillight and the side light share
one circuit... if two, then I am surprised. You can verify it with the good
If the voltage is present and same on both side, then you know it is that
light bulb panel is at fault... If your good side fits on the wire harness
of the bad side, then try it... and if that side light comes on... then you
definitely know it is the light bulb panel that is broken...