Circuit/System Description

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

When the ignition switch is placed in the START position, a signal is supplied to the K9 Body Control Module notifying it that the ignition is in the START position. Once a valid security message is received the K9 Body Control Module sends a message to the K20 Engine Control Module that crank has been requested. The K20 Engine Control Module verifies the security information is valid and that the transmission is in Park/Neutral. If it is, the K20 Engine Control Module supplies 12 V to the control circuit 625 of the KR27 Starter Relay, when this occurs, battery voltage is supplied through the switch of the KR27 Starter Relay to circuit 6 to engage the starter motor solenoid to allow the motor to spin. The K20 Engine Control Module also supplies 12 V to the control circuit 4325 of the KR27C Engine Restart Relay, when this occurs, battery voltage is supplied through the switch of the KR27C Engine Restart Relay to circuit 4358 to engage the starter motor pinion actuator solenoid, this allows the pinion actuator to kick out and engage the pinion with the flywheel.