Kevs57,

Wrenchbender's procedure is the ticket. It must be the large filament that is trying to light with the brakes. The only other snafu would be a damaged wire or connection from the drivers side light to the passenger side light. If the wire is just hanging on by a thread, it won't pass enough current to light the lamp.

A simple 'wiggle-tug-jerk' test usually turns up marginal wiring.

Stuart