4s-fe Ecu Pinout May 2026

Before testing sensors, you must verify the ECU is receiving clean power and has solid grounds. Switched +12V power from the EFI main relay.

Informs the ECU the engine is cranking so it can provide a richer fuel mixture for starting. Critical Sensors

These pins control the fuel injectors. On the 4S-FE, these are often "batch-fired" in pairs (1 & 3, 2 & 4). 4s-fe ecu pinout

Primary computer grounds (usually bolted to the intake manifold or cylinder head). E1: The main internal ground for the ECU logic circuit.

The output signal sent from the ECU to the igniter to trigger a spark. Before testing sensors, you must verify the ECU

Monitors engine heat to adjust fuel trim and idle speed.

The MAP sensor signal. This is the primary input the ECU uses to calculate engine load and fuel requirements. Critical Sensors These pins control the fuel injectors

A crucial "confirmation" signal sent back from the igniter to the ECU. If the ECU doesn't see IGF, it will cut fuel to prevent catalytic converter damage.