Some sources suggest it might be in the engine bay fuse box, while others point to the interior fuse box (under the dash). There's even mention of a potential location within the ECU (Engine Control Unit) area, but this is less likely.
To find it, you'll need to:
1. Consult your owner's manual: This is the best first step. The manual should have a diagram of the fuse and relay box(es).
2. Check both fuse boxes: Systematically examine both the engine bay fuse box and the interior fuse box, comparing the relays to diagrams found online (be careful searching, as different years may vary). Look for a relay labeled "FUEL PUMP," "EFI," or something similar. Sometimes relays are unmarked, requiring careful cross-referencing with diagrams.
3. Use a wiring diagram: A detailed wiring diagram specific to your 1990 Supra model (consider automatic vs. manual transmission) will be the most definitive way to locate the relay. You can often find these online through Toyota service manuals or repair websites.
4. Search online forums: Supra forums specific to the 1990 model year may have threads discussing fuel pump relay location and troubleshooting. This is a good resource if you can't find it in your manual or online diagrams.
Caution: Always disconnect the negative battery terminal before working with electrical components to avoid accidental shorts or injury.
