Chevythunder.com
Library.
you can find the wiring diagram for a camaro in either a chilton auto maunal or a haynes automanual
http://www.commandocaralarms.com/wiring/1989/Nissan/Pulsar
Try MOTORLIT.COM You can find the wiring diagram you need at autozone.com. that is where I go.
In any handbook which shows the wiring diagram for the F350 for that year.
You can find the heater wiring diagram for a 1989 Buick LeSabre in the vehicle's owner's manual. You can also obtain it from various auto part stores.
Your local Chevy dealer parts man can print that out for you.
You can obtain a wiring diagram of your Mitsubishi 1.5 liter at most Mitsubishi dealerships. You can also find the wiring diagram and many auto-parts stores.
Try Autozone.com
A complete diagram is available at MOTORLIT.COM.
crutchfield.com