When the engine starts cutting out under load, refuses to start when hot, or logs a hard-to-read check engine light, the first place a professional mechanic turns is the .
Always start with the pinout. Never throw parts at a diesel ECU until you verify voltage, ground, and signal at the pins. Part 8: Wire Color Variations (Prado vs. Hiace vs. Surf) Toyota changed wire colors slightly by model: 1kz ecu pinout
Bad injection pump ($2,000 repair quote). When the engine starts cutting out under load,
No start but cranking? Check Pin B1 (crank sensor) resistance should be 1.6–2.1 kΩ. If open, the ECU never fires the injectors. Connector C – Outputs & Communications (16P) | Pin | Wire Color | Function | Notes | |------|-------------|---------------------------|------------------------------| | C1 | Black | TC terminal (check engine light) | Switched ground – illuminates when fault exists | | C2 | White | Tachometer output | 12V square wave (diesel tach) | | C3 | Green | AC idle-up request | 12V when AC compressor on | | C5 | Orange | Diagnostic (SIL) | 9600 baud for Toyota scanner | | C6 | Blue/Red | EGR vacuum switching valve (VSV) | 12V control | | C9 | Yellow | Immobilizer communication (if equipped) | Serial data to transponder amp | | C10 | Brown/Red | Fuel heater relay | 12V below 5°C | | C12 | Pink | Idle-up VSV for power steering | 12V at steering load | Part 8: Wire Color Variations (Prado vs
| Model | Stop Solenoid (A14) | TPS Signal (B4) | Crank Sensor (B1) | |-------------------|-------------------|-------------------|---------------------| | KZJ70 Prado | Red/Black | Yellow/Green | Red/Blue | | KZJ90 Prado | Red/White | Yellow/Black | Blue/Black | | Hilux Surf | Red/Black | Green/Yellow | Red/Blue | | Hiace (Van) | Black/Yellow | Yellow/Green | Light Green/Black |
Pin A3 (ground) corrodes. Symptoms include random stalling and low injection pump pressure. Connector B – Sensor Inputs (22P) | Pin | Wire Color | Sensor | Signal (Key ON) | |------|-------------|---------------------------|------------------| | B1 | Red/Blue | Crankshaft position (NE) | AC 0.5-1.0V (cranking) | | B2 | White/Blue | Camshaft position (G signal) | AC 0.5-1.0V | | B4 | Yellow/Green | Throttle position sensor (VTA) | 0.5V idle – 4.5V WOT | | B6 | Brown/White | Engine coolant temp (THW) | 2.5V cold – 0.2V hot | | B7 | Green/Black | Intake air temp (THA) | 3.0V cold – 1.0V hot | | B9 | Pink/Blue | Boost pressure sensor (PIM) | 1.0V at 0 psi – 3.5V at 15 psi | | B13 | Violet/White | Vehicle speed sensor (SPD) | 0-5V pulse (AC) | | B18 | Blue/Yellow | Neutral start switch (NSW) | 0V in Park/Neutral; 12V in gear | | B20 | Gray | EGR lift sensor | 0.5-4.5V |