Wiring Tools
Anyone that's going to attempt a major, or minor for that matter, wiring job should invest in the proper tools. Quality wire strippers, terminal crimpers, a good test light, and a soldering gun beat the heck out of stripping wire with a penknife or your teeth, crimping terminals with a pair of pliers, assuming a circuit is live, and soldering with a cigarette lighter.
The Number One Problem
You can just about bet that the cause of 90 percent of all automotive electrical gremlins is caused by a bad grounding situation. Always keep in mind that a circuit, any circuit, has to be complete. This means that the current has to be able to travel from true ground to the positive side of the energy source in order to operate. Never rely on just the negative battery cable as the only ground, always incorporate a separate ground from the engine block to the chassis.
 Some of the tools you should...  Some of the tools you should have on hand whenever doing any kind of wiring are a good set of wire strippers, wire of the correct gauge for the job, and a good set of crimping pliers. |  A test light is a lifesaver,...  A test light is a lifesaver, allowing us to determine for sure when a circuit is live, rather than just making an assumption. |  A good soldering iron is a...  A good soldering iron is a must, as well. Though there are differences in thought, I prefer to solder my connections. This "cold-heat" iron works incredibly well. |
 Multi or OHM meters are handy...  Multi or OHM meters are handy gadgets, and they have saved me a lot of heartache and time when diagnosing problems or looking for short circuits. | | |