How do you get diagnostic codes for a 89 Toyota pickup truck?

Answer 1

next to the fuse box under the hood (left side) theres a small box that says diagnostics.
put a paperclip jumper between TE1 and E1 (marked with x's below)
____________
l l
l [ ] [ ] [ ] l
l [ ] [ ] [ ] l
l l
l [ ] [ ] l
l l
l [X] [ ] [ ] l
l [ ] [X] [ ] l
l [ ] [ ] [ ] l
l___________l

then put the key in the ignition and turn the key (dont start the truck just turn it so the dash lights come on)

the check engine light will flash on and off something like this
O_O_O_O_ _O_O so you would look up engine code 42 (O= on/ _ = off)

and here's a good site that lists all the codes www.troublecodes.net