These are critical for the ECU to "wake up" and communicate with diagnostic tools:

: Enthusiasts frequently swap K6A engines into older vehicles like the Suzuki Mehran. This requires matching the original ECU signals one-to-one with the new harness.

For this article, we focus on the most common performance variant: with the 56B0 or 56B4 ECU series. This is the sweet spot for tuners pushing 100+ HP from the 660cc turbo.

The K6A ECU uses three main connectors (A, B, C) on the 1998-2002 models.

| Pin | Signal | Notes | |------|-------------------|-------------------------------| | B2 | Injector 1 | Low-Z (2.5Ω), external resistor pack | | B3 | Injector 2 | | | B4 | Injector 3 | | | B10 | Ignition coil trigger 1 | 5V logic, goes to igniter module | | B11 | Ignition coil trigger 2 | Waste spark system | | B15 | Boost control solenoid | PWM duty cycle, 0–100% | | B18 | Idle air control (IACV) | Stepper motor – 4 wires (separate pins) | | B22 | Fuel pump relay | ECU grounds to prime/run | | B29 | Check engine light (MIL) | Switched ground, 12V feed from cluster | | B31 | O2 sensor signal (front) | Zirconia, 0.1–0.9V |