If you are unsure of what you are doing, get some knowledgeable help or hire a MECP certified installer.
If you are unsure of the circuits you are working on, consult the applicable wiring diagram. You should be able to purchase a vehicle specific wiring diagram from any Toyota dealer.
Disconnect your battery when working on electrical circuits.
When running power connections (+12V) off the battery, always fuse the line as close as you can to the battery.
When grounding a circuit, make the ground wire as short as possible and connect to a clean and solid chassis ground source.
The ground wire for a circuit should be the same gauge wire as the power wire for that circuit.
Consider the current draw and length of a planned wire run to determine the wire gauge required.
Consider the wire gauge and the current flow (in amps) when selecting a fuse size.
Always fuse a power wire after a SPDT relay.
Always fuse a power wire after changing wire gauge.
When tapping into an existing circuit to control additional lights etc., utilize a SPDT relay and a separate power connection from the battery or from a distribution block.
When tapping into an existing circuit, verify existing wires using a multimeter or voltage meter.
Solder and heatshrink wire connections if possible, tape is an alternative to heatshrink. 3M Scotchlok connectors are an alternative to soldering.
When using wire nuts, use the correct size for the wire gauge and the number of wires being connected.
Route wires in the engine compartment away from the heat (exhaust manifold) if possible- otherwise, protect the wire.
Use a blunt object to poke through existing grommets when passing wires to minimize the risk of damaging existing wires.
Place fuse holders and relays in accessible locations. It is better to keep relays within the confines of the cab, out of the weather when possible.
Document you electrical modifications on paper (schematic), so you can refer to them later if needed.
INFO: Common Sense Wiring Tips
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