The Heated Oxygen Sensor (HO2S) uses a high-current heater circuit. When the sensor insulation fails, it shorts the heater wire to the sensor signal wire, backfeeding voltage into ECU pin E5.
If your Daihatsu Hijet EFSE is dead, follow this flowchart using the pinout above:
The ECU sends out a regulated 5V to power the sensors. A short in any sensor can pull this "hot 5V" to zero. daihatsu hijet efse ecu pinout hot
| Pin # | Sensor | Wire Color | Voltage | | :--- | :--- | :--- | :--- | | C1 | Throttle Position Sensor (TPS) +5V | Light Green (L-G) | 5.0V | | C2 | Manifold Absolute Pressure (MAP) +5V | Light Green/Red (L-R) | 5.0V | | C3 | Crankshaft Position Sensor (Ne) | Shielded White | 2.0V AC (Cranking) |
Warning: If you short pin C1 or C2 to ground, the ECU will die instantly. Never pierce these 5V reference wires with a test light connected to battery positive. The Heated Oxygen Sensor (HO2S) uses a high-current
The subject line mentions "hot," which is the most common complaint with the Hijet EFSE system. Many owners find their truck starts perfectly cold but refuses to start after driving for 20 minutes and turning it off (a classic heat-soak issue).
Here is how the pinout relates to this problem: Scenario B: The EFI Main Relay (The "Hot"
Scenario A: The IACV/ISC Valve On the EFSE, the Idle Air Control Valve is electronically controlled by the ECU (look for the ISC pins on the connector).
Scenario B: The EFI Main Relay (The "Hot" Relay Failure) This is arguably the most common failure point on 90s/00s Japanese Kei trucks.
Scenario C: The Temperature Sensor (THW) If the THW sensor (connected to the THW pin on the ECU) reads incorrectly due to heat soak, the ECU injects too much fuel (choke) into a hot engine.