Where is the fuel pump relay on a 1992 Lexus sc300?
The fuel pump relay on a 1992 Lexus SC300 is typically located in the engine bay inside the main under-hood fuse/relay block on the passenger side near the strut tower, and it is usually labeled EFI or FUEL PUMP. This short answer helps you identify the likely spot before you dive into the details.
The 1992 SC300 uses the 2JZ-GE engine, and like many Toyota-Lexus designs of the era, the fuel pump is controlled by a dedicated relay within the under-hood fuse box. If you don’t immediately find it there, your car’s wiring diagram or the lid diagram on the fuse box cover will guide you to the exact pin and label. This article walks through where to look, how to verify the correct relay, and steps to test or replace it safely.
Where to look in the engine bay
Before you start, understand that there are two common relay locations on many SC300s and their Toyota-Lexus siblings: the large under-hood fuse/relay box and, less commonly, a secondary relay in an interior fuse box. The following list focuses on the engine bay location first, with a note on alternatives if necessary.
- The primary under-hood fuse/relay box, located on the passenger side near the strut tower. Look for a relay labeled EFI, FUEL PUMP, or similar wording on the top or side of the relay.
- Within the same box, check the diagram on the lid to confirm the exact position of the fuel pump relay and ensure you’re selecting the correct one before swapping.
- If the relay isn’t in the under-hood box, a secondary EFI or fuel-pump-related relay can sometimes be found in the interior fuse box under the driver's side dash. Check the fuse box cover for labeling and reseat or swap with a similar relay if needed.
Understanding these common locations will save time and prevent unnecessary disassembly. If the diagram on the fuse box is faded or unclear, taking a photo with your phone to cross-check labels can be a quick workaround.
Concluding the location search, always compare the exact labeling on the relay with the cover diagram, because different markets or model years may use slightly different terminology for the same component.
How to verify and replace the relay
- With the ignition off, locate the under-hood fuse/relay box and identify the fuel pump/EFI relay using the lid diagram. Remove the relay gently by pulling straight up.
- Inspect the relay for signs of wear such as burning, cracking, or corrosion on the terminals. If you notice any damage, replace it.
- Test the relay by swapping it with another relay of the same type and amperage from the same box (for example, a cooling fan or A/C relay, if it’s the same amperage). If the fuel pump runs with the swapped relay, the original relay is faulty.
- While testing, verify the fuse corresponding to the fuel pump/EFI circuit is intact (pull the fuse and inspect for a broken wire or a darkened element). Replace the fuse if necessary.
- If swapping relays doesn’t restore fuel pump activity, test the fuel pump circuit at the pump connector for 12V when the ignition is ON. If voltage is present but the pump doesn’t run, the pump or wiring may be at fault.
After completing the test, reinstall the original relay if you’ve determined it’s still functional, or keep a working spare on hand if you’re performing ongoing diagnostics.
What to do if you can’t locate it
If your SC300 path to the fuel pump relay isn’t yielding results, consult the factory service manual or a trusted automotive technician. Some models and markets may have variations in relay placement, and wiring diagrams tailored to your exact VIN can be invaluable for an accurate diagnosis.
Notes for careful troubleshooting: work in a dry, well-lit area; disconnect the battery before removing or reseating electrical components; and avoid touching corroded terminals with bare skin. When in doubt, seek professional help to prevent electrical shorts or fuel system hazards.
Summary: For a 1992 Lexus SC300, start with the under-hood fuse/relay box on the passenger side near the strut tower and look for a relay labeled EFI or FUEL PUMP. If not there, check the interior fuse box under the dash. Use the lid diagram to locate the exact relay, test with a known-good relay, and verify fuses and pump voltage to confirm operation. A careful, labeled inspection usually reveals the right relay and helps you avoid unnecessary disassembly.
