Integrated Body Control Unit (IBU: SMK + BCM + TPMS) & Vehicle Control Unit (VCU)
When turning the ignition switch or EV READY on, the VCU begins communication with the IBU (SMK + BCM + TPMS) by sending a VIN (Vehicle Identification Number) request signal for the operation of the vehicle and the motor.
The IBU (SMK + BCM + TPMS) sends an "Ignition Approval Not Possible" signal to the VCU when the Immobilizer cannot perform ignition. In this case, the VCU enters an ignition inhibition state and the motor cannot be operated.
On the other hand, the IBU (SMK + BCM + TPMS) sends an "Ignition Approval" signal to the VCU including the VIN and learnt status information when the Immobilizer can turn the "EV READY" mode on.
Information regarding an Immobilizer is stored in two separate areas of the EEPROM inside the VCU. The VCU checks both types of the information before the Immobilizer Authentication process. When the VCU confirms that they correspond, the Immobilizer Authentication begins. If they do not, the VCU stops the authentication and store the "ECM Memory Error" DTC. When this occurs, the Limp Home function cannot be performed. If the problem persists after registering a new key, the VCU must be replaced.
The Smart Key system (SMK) consists of a IBU (SMK + BCM + TPMS), power distribution module (PDM), external receiver, and Smart Key holder integration. On the other than, the SMK (smart key) system without a FOB holder has an embedded Demodulator which is connected to the SSB with two immobilization coil lines. The Smart Key unit transmits authentic signals to the VCU and receives an "EV READY ON" signal to have the vehicle ready through this process.
This function allows a driver to drive the vehicle by turning on the ignition switch twice before registering its key. It can be implemented only when the VCU and the Smart Key system (TP, SMK) are virgin. EV READY "ON" follows the steps below.
Perform the following steps when both the VCU and the smart key system are in the "Virgin" state.
- At first ignition, turn on the ignition switch between 0.5 and 1.5 second.
- Turn the ignition switch OFF between 0.2 and 1.5 second.