Minimum wire harness for engine operation?

[CTScott]

Originally Posted by CrankyOldMan

Just a quick update on ECU connectors.

E7 (26 pin) is required, as it connects the injectors, ignition coils, crankshaft and camshaft position sensors, and oil control valve (VVT-I). It also connects the idle air control valve and VSV (EVAP) coil.

E6 (16 pin) is required, as it connects the MAF sensor, throttle position sensor, knock sensor, and primary oxygen sensor. It also connects the engine temperature sensor (may be needed for warmup/idle) and some unneeded things: max hot/foot mode sw, power steering pressure sensor, vapor canister pressure sensor, and a few others that I can't track down at the moment. The secondary O2 sensor is connected via one of the internal wire-wire connector blocks, but it may be optional as well.

E5 (12 pin) is only required if the ECU requires speedometer input, or if you have an automatic transmission (ewww!).

E4 (22 pin) seems to be optional for everything except the combination meter, unless the BATT signal on pin 1 is something other than battery voltage sense.

Also got some info on the diagnostics, since it's NOT CAN-based OBD-II. It's M-OBD on pin 7 (SIL) and uses a different protocol--possibly covered elsewhere in the forums.

M-OBD is a Japan-only thing. The Echos did predate CAN, but were standard ISO9141 for OBD.