Modes of Operation

Secondary Electric Drive 

The Secondary Electric Drive system is optional for customers who desire AWD capability and increased performance. The secondary Electric Drive powers the front wheels, and is not mechanically connected to the Primary Electric Drive system that powers the rear wheels. The Secondary ISC (S-ISC) receives its commands from the Primary Drive's Inverter System Controller (ISC), and can operate in two basic modes:

• Torque Control Mode - The S-ISC will receive a torque command from the ISC to help propel or brake the vehicle. Regenerative braking is split between the two axles to optimize vehicle efficiency and vehicle stability. Acceleration torque is likewise split between the Front (Secondary) and Rear (Primary) axles to maximize efficiency, performance, and handling.
• Speed Control Mode - The S-ISC can receive a speed control command from the PCM and ISC in certain wheel slip events to maintain vehicle stability and maximize vehicle handling on slippery road surfaces. The S-ISC in all cases is under the direction and control of the ISC.

The S-ISC follows the ISC for all vehicle powerup and powerdown procedures. It conducts its own safety and functional checks during every system powerup, and assists with HV electrical discharge during every system power-down.

If either the S-ISC or the ISC are faulted, the remaining ISC will be used to drive the vehicle with reduced performance.