My theory on diagnosing any problems is "whats the easiest thing to fix?" and I try that first. Check your fuses (under the side cover on the left) first and make sure its still good.
After that, check your bulbs, although if none of them are working, i find it hard to believe that all 4 are burned out.
If that doesnt fix it, start tracing wires. Start at the signal and follow the wires, making sure all the connectors are snug and not corroded. There is a wiring diagram on here somewhere that will make it easier for you to follow the wires.
If that still doesnt fix it, check your flasher relay (under the same side cover I think), if thats gone bad, it may not allow any current to your signals, but i could be wrong about that.
If none of these things help, then you are past my limited knowledge. Hope this helps!
