Behind glove box or passenger kick panel. Connector types: Main 26-pin (A) and 12-pin (B) or similar.

| Pin | Wire Color | Signal | Description | |------|------------|--------|-------------------------------| | A1 | B-R | +B | Main EFI relay power | | A2 | B-Y | +B1 | ECU backup power (constant) | | A3 | B-O | E1 | Power ground | | A4 | W-B | E01 | Injector/ignition ground | | A5 | B | E02 | Injector/ignition ground | | A6 | Y | #10 | Injector 1 & 4 trigger | | A7 | L | #20 | Injector 2 & 3 trigger | | A8 | G | IGF | Ignition confirmation signal | | A9 | W | IGT | Ignition timing signal to igniter | | A10 | R | STA | Starter signal (from ignition switch) | | A11 | B-W | NSW | Neutral start switch (auto) | | A12 | V-W | SPD | Speed sensor input |

If you are in the US, AutoZone’s website has a "Repair Help" section. Once you register (free), you can access wiring diagrams for specific 3S-FE vehicles (e.g., 1994 Toyota Camry). They often provide a simplified pinout.

Manages sensor inputs including the Crankshaft position sensor (NE+) , Camshaft position sensor (G+) , and Throttle position sensor (VTA) .

Connector A (often large, primary):

| Task | Recommendation | |------|----------------| | | Use a high‑impedance multimeter or an oscilloscope with a 10 MΩ probe to avoid loading the circuit. | | Adding Sensors | Insert a splice block (e.g., Molex Mini‑Fit) rather than cutting wires; keep wire gauge consistent (typically 18‑22 AWG). | | Boost Controller Wiring | Connect to the MAP sensor line through a diode (1 N4007) to prevent back‑feeding voltage into the ECU. | | ECU Removal | Disconnect the battery for at least 5 minutes to clear residual charge; label each connector before unplugging. | | Firmware Updates | Use the dedicated diagnostic port (Pin 16) with a JTAG adapter; never power the ECU while flashing unless the tool explicitly supports it. |