Toyota 89661 Ecu Pinout |best| Jun 2026

2. Grey/White OBD1 & Early OBD2 Era (Mid 1990s – Early 2000s)

: Switched 12V power inputs from the EFI Main Relay. toyota 89661 ecu pinout

: Diagnostic feedback communication pin (found on older OBD1 diagnostic boxes). : Toyota wiring diagrams are almost always drawn

: Toyota wiring diagrams are almost always drawn looking directly into the face of the wire harness plugs , not the pins on the metal ECU box itself. Look for the plastic locking tab orientation on the diagram to ensure you aren't looking at it upside down or mirrored. Main switched 12V power coming from the EFI main relay

If you cannot find a reliable diagram online, Toyota provided an excellent fail-safe mechanism on many 89661 ECUs.

Main switched 12V power coming from the EFI main relay.

Starter motor signal (tells ECU the engine is actively cranking). Step-by-Step Guide to Identifying Unknown 89661 Pinouts