Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
K20 Engine Control Module
The K20 Engine Control Module monitors the S126 Drive Mode Select Switch as an input. The K20 Engine Control Module applies 5 volts to the switch resistor ladder and monitors the signal voltage from the switch. As the switch is rotated to the left or right, current flows through different resistors and the voltage monitored at the K20 Engine Control Module also changes. The K20 Engine Control Module uses this voltage change to determine if the rotary knob is in the at rest position or has been turned left/right. The K20 Engine Control Module will change the drive mode based on this input.
When a drive mode change is requested by the drive through the S126 Drive Mode Select Switch, the K20 Engine Control Module will broadcast a message to all modules indicating the requested drive mode. Control modules that are involved in changing their operation based on differing drive modes will then change their operating values. The K20 Engine Control Module may also change operating values based on the drive mode, such as a more or less aggressive throttle profile.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.