Limited Slip Differential Description and Operation (With G96)

Fig 1: Rear Drive Axle Block Diagram (With G96)

Courtesy of GENERAL MOTORS COMPANY

The rear differential clutch control modules function is to control the electronic limited slip differential. The rear differential control module receives a torque command signal from the chassis control module (CCM) according to the driving situation to achieve vehicle dynamics and traction.

The electronic limited slip differential system contains the following main components:

• The rear differential clutch control module
• The rear differential oil pressure/temperature sensor
• The differential clutch pump
• The rear differential clutch solenoid valve
• The rear differential oil temperature sensor

When the torque signal is received, the rear differential control module actuates the following components:

• Differential clutch pump (bi-directional rotary piston pump)
• Rear differential clutch solenoid valve (fail-safe pressure relief)

The electro-hydraulic piston actuation engages the limited slip clutch to allow active variable locking torque transfer to the left and right half shafts.

The rear differential clutch control module monitors voltage levels, hydraulic and clutch sump temperatures, over-current, and circuit failures.

During normal operation, the vehicle will run a bleed process on the system to maintain system performance. The bleed cycle will run after every third key cycle with a minimum key off soak time of 30 min. While the bleed is being process is running a buzzing or whirring noise may be audible.

If replacing the rear differential clutch control module, the module needs to be programmed/configured with a rear differential clutch service calibration value. The clutch calibration service value is an alphanumeric value that is stored in the rear differential clutch control module and stamped on the rear differential clutch pack housing. The clutch classification value is based on the pressure-to-torque performance of the individual clutch pack. The clutch classification helps to improve vehicle performance by adjusting software parameters to suit the mechanical hardware.

Configuring the rear differential clutch control module with the clutch classification value might be required after certain service procedures are performed. A two digit value will be used during the programming of the rear differential clutch control module using the scan tool.