The Haynes manual for your vehilce (available in autoparts stores) is one place to look. Most Ford Service departments also have them, but it may take a little extra effort to get someone there to share them. The problem with Ford Pickups brake light and blinker system is usually the ground part of the circuit, particularly in pickups with rust. Try connecting a test light to the bumper (or anywhere you see bare metal) and checking the connector with the bulb removed. This will tell you if you have a bad wire, or a bad ground (if the test light doesn't light at all, this indicates an open, check your test lights ground connection and try again. Often it is helpful to try using the test light on a working light to see if the test light has a good ground first)
Wiring diagram of what component?
A Ford Ranger pickup truck wiring diagram can be obtained from most Ford dealerships. The wiring diagram can also be found at most auto-parts stores.
A wiring diagram for a 1994 Ford Ranger can be found in the Chilton's manual for that vehicle. You can also find this wiring diagram at most auto parts stores.
There is no such thing as a free wiring diagram
spark plugs wiring diagram
wiring diagram for 98 ford ranger door alarm
Most repair manuals have the wiring diagrams in them.
Haynes Repair manual has the wiring diagrams for your vehicle in section #12-28
http://www.eautorepair.net
autozone.com has online manuals
You might try the public library. They have amazing stuff. I found a wiring diagram for a 56 Chevy at mine! All the best!
i cannot get the brake lights to work