To help narrow down your wiring or documentation search, let me know the the engine came from, or the OEM part number on the ECU casing. I can also help you troubleshoot specific engine symptoms or guide you through a standalone ECU conversion . Share public link
Outputs a regulated 5V reference voltage to the MAP and TPS sensors. Ignition & Fuel Control Terminals Terminal Label Description Wiring Function Ignition Timing Signal
2. Standard 3S-FE ECU Pinout Reference (Common Gen 2/3 MAP-Based)
: Always check whether the PDF diagram illustrates the pinout from the wire side (harness plug looking from the back) or the component side (looking directly into the ECU female pins). Misinterpreting this layout can mirror your wiring and fry the ECU circuitry. To help tailor this guide further, please share: The exact model year and vehicle name of your 3S-FE engine. The 10-digit part number printed on your ECU casing.
Look at the sticker on your ECU casing. It will follow a format like 89661-xxxxx . Search specifically for this part number when looking up diagrams.
If you are dealing with a no-start scenario, rough idling, or wiring a swap, the ECU pins offer direct troubleshooting access points before you tear down mechanical components.
: Oxygen sensor signal used to manage air-fuel ratios in closed-loop mode. Ignition and Timing Signals
Connect a 12V test light or Noid light across the #10 pin and a positive power source. While cranking, the light should flash rapidly. If it stays solid or dark, the ECU is not grounding the injectors. Downloading 3S-FE ECU Pinout PDFs
Switched 12V power from the EFI main relay (active when the ignition is ON).
+12V directly from the battery (fused) to maintain ECU memory (KAM). Engine Ground
The 3S-FE relies on precise timing signals to fire the spark plugs.
The Toyota 3S-FE is one of the most reliable and widely produced 2.0-liter inline-four engines of the 1980s and 1990s. Found in popular vehicles like the Camry, Celica, RAV4, and Corona, this engine is a favorite for budget builds, restorations, and engine swaps.
: Intake air temperature sensor input.
Check the pin while cranking. You should see a small voltage pulse.
To help narrow down your wiring or documentation search, let me know the the engine came from, or the OEM part number on the ECU casing. I can also help you troubleshoot specific engine symptoms or guide you through a standalone ECU conversion . Share public link
Outputs a regulated 5V reference voltage to the MAP and TPS sensors. Ignition & Fuel Control Terminals Terminal Label Description Wiring Function Ignition Timing Signal
2. Standard 3S-FE ECU Pinout Reference (Common Gen 2/3 MAP-Based)
: Always check whether the PDF diagram illustrates the pinout from the wire side (harness plug looking from the back) or the component side (looking directly into the ECU female pins). Misinterpreting this layout can mirror your wiring and fry the ECU circuitry. To help tailor this guide further, please share: The exact model year and vehicle name of your 3S-FE engine. The 10-digit part number printed on your ECU casing. 3s-fe ecu pinout pdf
Look at the sticker on your ECU casing. It will follow a format like 89661-xxxxx . Search specifically for this part number when looking up diagrams.
If you are dealing with a no-start scenario, rough idling, or wiring a swap, the ECU pins offer direct troubleshooting access points before you tear down mechanical components.
: Oxygen sensor signal used to manage air-fuel ratios in closed-loop mode. Ignition and Timing Signals To help narrow down your wiring or documentation
Connect a 12V test light or Noid light across the #10 pin and a positive power source. While cranking, the light should flash rapidly. If it stays solid or dark, the ECU is not grounding the injectors. Downloading 3S-FE ECU Pinout PDFs
Switched 12V power from the EFI main relay (active when the ignition is ON).
+12V directly from the battery (fused) to maintain ECU memory (KAM). Engine Ground Ignition & Fuel Control Terminals Terminal Label Description
The 3S-FE relies on precise timing signals to fire the spark plugs.
The Toyota 3S-FE is one of the most reliable and widely produced 2.0-liter inline-four engines of the 1980s and 1990s. Found in popular vehicles like the Camry, Celica, RAV4, and Corona, this engine is a favorite for budget builds, restorations, and engine swaps.
: Intake air temperature sensor input.
Check the pin while cranking. You should see a small voltage pulse.