These scans are from the manual for export spec models (NOTE: if they don't come out right click and "save target as").
ECU/Power Source diagrams Diag 1 (154K) Diag 2 (176K) Diag 3 (140K)
Engine bay plug locations Diag 1 (168K) Diag 2 (144K) Diag 3 (73K) Diag 4 (114K)
Here are scans from the Japanese wiring diagram for the SW20. They are reasonably large, so be warned!
I'll assume you have some knowledge of Toyota wiring diagrams. These are in Japanese, but use the same format.
Series II-IV 3S-GE
Engine bay plug locations Diag 1 (309K) Diag 2 (327K)
EFI Schematic Diag 3 (270K) Diag 4 (138K)
Series II-V 3S-GTE
Engine bay plug locations Diag 5 (325K) Diag 6 (311K)
EFI Schematic Diag 7 (284K) Diag 8 (220K)
Ignition Diag 9 (135K)
Information Source: gtfour.supras.org.nz/diagrams.htm