MadMax, um, let's see how good I am at explaining this.
The left rear and left front are on one circuit.
The right rear and right front are on one circuit.
The "idiot" light on the dash is hooked to both circuits.
I haven't checked this, but I think the relay is also hooked to both circuits.
Meaning, you have you're "left loop" turn signals, and "right loop" turn signals, each loop sharing the "idiot" dashboard light and relay.
The relay works off of a certain amount of resistance, which means it needs both the front and rear turn signals to work in order to flash. If one is burned out, or not connected, the entire system just stays on. Manufacturers design the relay specifically in this way, so that you know when you have a bulb out....
Now that I think about it though, I think I might have seen two relays side by side just behind the battery tray... I'll check and see this weekend when I tear her open again and let you know, if somebody else doesn't get you a definitive answer first...
I highly doubt it's the relay, but an easy way to test is by swapping the front left and rights... You know the left side works, so plug in the right "non-functioning" light, and see what happens....