This may help you. http://www.installdr.com
You can get a free 2003 Ford Explorer Sport Trac wiring diagram online at the Modified Life website. You can also find this diagram in the Ford owner's manual online at Ford.com.
call at cpi Canada and ask them to fax you the diagram
Buy the Haynes Repair Manual for that vehicle
www.jeepforum.com lots of help from the members.
Go to www.the12volt.com they will have diagram your looking for FREE..
In a service manual at a dealer, parts store, or library.
Wiring for 91 Pontiac Transport: http://www.auto-olds.ru/PONTIAC%20TRANS%20SPORT%201991.pdf
The Chiltons and Haynes repair manuals will have the wiring diagrams. I have a 94 Trans Sport SE. I have both of those guides and they cover 1990 - 1999 Trans Sports.
Is the battery dead? Check for 12v on the main alternator cable. If no power, check for burned out fusible links between alternator and battery. You may need a wiring diagram to check further.
Go to a library or parts store and rent/buy a service manual.
Buy a Chiltons or a Haynes book at a parts store. Like $15