Ensure 12V is present when the key is in the "On" position.
Check Engine Light (CEL) trigger. Grounding this pin via a bulb illuminates the dash light. Troubleshooting Common Issues No Start Condition
Below are the most critical pins you will encounter when wiring or troubleshooting. Note that colors may vary slightly by year, but pin locations generally remain consistent within specific generations. 1. Power and Ground Signals These pins ensure the ECU turns on and stays grounded. 12V Switched Power (from the EFI main relay). BATT: Permanent 12V Power (for memory/fault codes). toyota 4afe ecu pinout
Camshaft position signals (used for sequential injection timing). 3. Fuel and Air Sensors
The signal from the MAP sensor. THA: Intake Air Temperature sensor signal. THW: Coolant Temperature sensor signal. Ensure 12V is present when the key is in the "On" position
Controls the bypass air valve to maintain idle under load.
If the igniter is bad, the ECU won't receive the "feedback" signal and will stop firing the injectors after a few seconds. Rough Idle or Stalling Troubleshooting Common Issues No Start Condition Below are
Oxygen Sensor signal (monitors exhaust lean/rich conditions). VTA: Throttle Position Sensor (TPS) signal. 4. Output Actuators
Once I have those details, I can provide a specific pin-by-pin chart for your exact harness.