no sweat Stuart, you are way ahead of me on the electrical end of these old trucks.
Petmil...the only thing I would add (or change) to what automarc has said is that if you are new to using a VOM (volt/ohm meter) I would suggest getting a digital unit. They are quite inexpensive (about $25 for one that is sufficient) and they will give a readout of the function so there is less confusion in understanding the scale. Basically you set the function to continuity (ohms = resistance), you should now have a reading of 1 (showing infinite resistance = open circuit) touch the 2 probes together and you will have a reading of 000 (zero resistance = complete circuit). You do that to verify the meter is working correctly. Next, WITH NO POWER TO THE SWITCH, touch one probe to the battery post of the switch, turn the switch on and watch the readings as you test continuity through each post on the switch. Some switches have more than one on position (parking lights vs. headlights). Be sure to test each post from the battery post at each on position as some lights (taillights & dash lights) will actuate on both positions. Any reading will tell you there is a continuous circuit between these posts at that switch position. Lack of a readout means that post is not actuated with switch in that position (either because it isnt supposed to actuate OR something is faulty). When checking the dash lights you will get varying reading between battery post and dashlight post as you turn the reostat. That will show the correct operation of the reostat in the switch. Good luck and have fun...
Carl
