looks like you have a problem on you're compressor circuit.
I'm assuming that this is a pretty small unit...On you're circuit you should have a start relay/overload located on the compressor connection itself and a capacitor.
To troubleshoot this you will need a multimeter set on ohm, to check resistance from the compressor to ground.
Once you have pull the plastic relay from the compressor (power should be disconnected by now!) You will exposed 3 connectors on the compressor. Put 1 probe on the compressor casing and move the other probe to the 3 connectors on the comp. If you have any resistance (if you ear a beep) you have a grounded compressor and that's that, might as well give up now and get yourself a new one.
I can tell you how to check the capacitor and the relay if the compressor check out OK. my name is Benge (nick name Benge007)
Let me know, I'm knew at Fixya, I'm just doing this for fun, free
Click on this site. This is the manual for you brake system. Looks like it might have the plug info in it also
Hope this helps
are we using basic trouble shooting techniques begin were there is curen t and work in reverse .when you come to a point were there is no current start repair work. you can use a 12v light or a basic 12 v meter.is there a fuse problem.
Shouldn't be too hard. Which engine do you have with which carburettor? I will be happy to send you some diagrams as soon as I know a little more.
you would be better obtaining a cheap multimeter and test the continuity of the wiring. Or check the contacts were the bulbs sits. you can use a finger emery board to clean the contacts, hope this is of use.