Is there an easy way to find a short or open circuit in a car?

I am trying to find a open or short circuit that is on a wire which is in a harness with other wires, on a 1986 Mazda B2000 truck. With so many of you having expertise in electronics, I thought here would be a good place to post my question. Does anyone have any suggestions how to find this open or short-circuit?

I am open to the idea of getting a short-circuit-finder. Though I am not sure what features I should look for if I decide to get one. Does anyone have any suggestions?

a) Does anyone know if these work well?

b) What features should I look for If I get one?

c) Do you have any other on a short circuit finder? type, manufacturer, model etc

Below is a link to a site that uses a short circuit finder to find a short circuit, and has information on using one: http://inliners.org/tech/tech6.html

Below is a link to a site that tells about how a tone generator is used to find a short circuit, in a home environment (I think this is how most short circuit finders work): http://askville.amazon.com/tone-gene...uestId=5912724

I found some links that seem to show that it is possible to make a signal generator and tracer, but the pages with the schematics would not load. A list of tools with links to tools and their schematics
http://www.qsl.net/kc4gzx/kc4gzx/project20.htm

Circuit tracer (neither of these would not load 4-3-09 kept getting message "the Connection was reset."):
should have schematic:
http://circuitos.tripod.cl/schem/r111.gif
and the signal generator:
http://circuitos.tripod.cl/schem/r25.gif

A little paranoid voice thinks this Instructable has some clues to the solution: How to prevent thefts steal your motorcycle for less than US$ 2

Thank-you in advance,