Tom R,
The meter I refer to is generally called a VoltOhmMeter...VOM meter. It will read all those values. Some have a "buzzer" feature so when you touch each end to something that has continuity, it will make a noise...you can keep your eye on the work and listen for the buzz.
The key switch is sometimes marked. The center post is usually power and each post around the perimeter would be Accessory--Start--Run. Your truck might not have all these features. Again, this could be figured out with the ohmmeter.
You stick one lead on the center post and the other on one of the posts around the outside. When you turn the key, the meter will buzz when there is a circuit between the leads...continuity! You know that start/run is all the way turned..find the buzz. You know that accessory ISN'T start/run, but another key position...find the buzz.
This is all done with the device disconnected from the wires. If you need to identify a wire that goes from under the dash to the back of the truck for instance, you ground the wire at the back of the truck, attach a meter lead to ground near the dash and start touching wires with the other lead...when you get to the wire you were hunting for..bingo, the meter will buzz!
You really don't have to have numbers on wires, or colors for that matter. It makes it much easier, but with a meter and common sense you can work around it.
Wire size is important. Certain circuits carry charging loads, or horn loads or lighting loads. This is where the manufacturer hopefully did his homework.
I am sure you get the idea. Think of it as a jigsaw puzzle. As you run the wire from the starter to the ammeter, put a little X on this wire in the diagram...all taken care of! When every wired is crossed off...make a run to the liquor store for some Night Train Express!
Again, I am sorry for the novel, but if you ask, I will try and answer.
Stuart
