Permanent +12V feed from the battery for the ECU’s internal memory (Keep Alive Memory).
: Injector pulse signals (usually batch-fired on these older units). : Intake manifold pressure signal (MAP sensor). : Intake air temperature. : Coolant temperature. : Throttle position sensor (TPS) and idle switch. : Oxygen sensor signal.
Always verify pinout with a factory wiring diagram for your exact (e.g., 89661-1A630, 89661-20220). Wire colors and pin functions changed between model years, transmissions, and markets.
"That's not good," he mumbled. He checked the
Early 1990s 4S-FE ECUs often utilize a or 26P / 16P / 12P connector setup. For the most accurate results when wiring, it is highly recommended to open the ECU casing and look for the etched labels (e.g., "STA", "IDL", "+B") directly on the PCB.
He knelt by the passenger kick panel where the ECU lived, buried behind the carpet. He unplugged the harness connector. It was a mess of cut wires and splices.
