Transmission - Transmission - System Operation and Component Description

Description and Operation

System Diagram

System Operation

Network Message Chart

Broadcast Message	Originating Module	Message Purpose
PATS security data	GWM	The GWM relays PATS status to allow or prohibit electric drive operation.
ABS Active	ABS	The ABS module indicates activity to the TCM.
Transmission HV Discharge Command	PCM	The PCM commands the TCM to discharge the high voltage capacitors.
Traction Battery Voltage	BECM	The BECM relays the current HVTB voltage.
Traction Battery Contactor Command	BECM	The BECM indicates that the contactors are opening or closing.
Motor A Torque Request	PCM	The PCM commands a specified output torque from the electric motor.
Inverter Coolant Temperature	PCM	The PCM relays coolant temperature at the high voltage inverters.
DC/DC High Voltage	DCDC	The DC/DC converter reports HV bus voltage.
Odometer Master Value	GWM	The GWM shares the master odometer count with all EV HS-CAN modules.

Park

When the selector lever is in the park position, the TR (transmission range) sensor sends a signal of 4.20-4.50 volts to the PCM (powertrain control module) on pins 1-2 and 0.60-0.90 volts on pins 4-5. The park pawl locks the final drive to the gearbox. Voltage is not supplied to the electric motor.

Reverse

When the selector lever is in the reverse position, the TR sensor sends a signal of 3.40-3.70 volts to the PCM on pins 1-2 and 1.40-1.70 volts on pins 4-5. The vehicle can only be operated in a rearward direction and the reversing lamps are illuminated. The PCM sends a signal to theTCM (transmission control module) to supply voltage to the electric motor with reverse polarity based off of theTR sensor signal.

Neutral

When the selector lever is in the neutral position, the TR sensor sends a signal of 2.60-2.90 volts to the PCM on pins 1-2 and 2.20-2.50 volts on pins 4-5. The electric motor does not input any torque to the gearbox. Voltage is removed from the electric motor.

Drive

When the selector lever is in the drive position, the TR sensor sends a signal of 1.80-2.10 volts to the PCM on pins 1-2 and 3-3.30 volts on pins 4-5. The PCM sends a signal to the TCM to supply voltage to the electric motor based off of theTR sensor signal.

Low

When the selector lever is in the low position, the TR sensor sends a signal of 1-1.30 volts to the PCM on pins 1-2 and 3.80-4.10 volts on pins 4-5. The PCM sends a signal to the TCM to supply voltage to the electric motor based off of theTR sensor signal. In low, conventional low position is simulated with limited RPM and engine braking is simulated through the regenerative braking.

Component Description

SINGLE-SPEED REDUCTION GEAR

• Differential
• Intermediate shaft assembly
• Input gear

The single speed gear reduction transmission has an input gear assembly, intermediate shaft assembly and a differential assembly.

The input gear is pressed into a bearing retained in the motor housing by a snap ring and has 2 inner roller bearings that allows it to spin on the RH (right-hand) outer surface of the differential. The input gear transfers torque from the electric motor to the intermediate shaft assembly.

The intermediate shaft assembly spins on a bearing that is pressed into the motor housing and a bearing that is pressed into the gearbox housing. The intermediate shaft assembly has the park gear splined to it. The intermediate shaft transfers torque from the input gear to the differential ring gear.

The differential spins on 2 roller bearings housed in the input gear and a bearing that is retained by a snap ring in the gearbox housing. The differential is a conventional type with 2 pinion gears supported by a pinion shaft and 2 side gears supported by the differential case, the LH(left-hand) halfshaft and the transfer shaft (which splines to the RH halfshaft).

The gear reduction transmission has a final drive ratio of 7.82:1.

PARK PAWL MECHANISM

• Park pawl actuator rod
• Park pawl abutment
• Park pawl
• Park pawl gear
• Park pawl retaining pins

The park gear is located on the intermediate shaft assembly. There are lugs around the outer diameter of the park gear to allow the park pawl to hold the park gear stationary to the motor housing, which holds the differential in place and keeps the vehicle from moving. The park pawl is pinned to the electric motor housing and the gear housing. The park pawl actuator rod is connected to the manual shaft detent plate and pushes the park pawl into the park gear when park is selected.

TR SENSOR

•  TR sensor
• Manual control lever
• Manual control lever shaft bolt

The TR sensor has a 6-pin connector. The TR sensor is bolted to the gear box housing and is keyed to the manual shaft by a flat keyway. The manual shaft is turned by the selector lever linkage and the manual lever. The TR sensor sends a signal to the PCM to start the vehicle in PARK and NEUTRAL. The TR sensor opens/closes a set of 4 switches that are monitored by the PCM to determine the position of the manual lever (P, R, N, D, L). The TR sensor is not adjustable.

TCM

The primary purpose of the TCM is to convert high-voltage DC current into 3-phase AC current to supply the field coils of the electric motor when requested by the PCM. This is accomplished through the use of inverters and internal speed sensors. Additionally, the TCM carries out regenerative braking when requested by the brake system control module (BSCM) by reconfiguring the electric motor to act as a generator. This decelerates the vehicle and returns energy to the high voltage traction battery (HVTB), extending vehicle range.

The TCM also serves as a high-voltage DC junction box, distributing fused high-voltage DC to the following underhood components:

• DC/DC converter
• Air conditioning compressor module (ACCM)
• Electric supplemental PTC (positive temperature coefficient) heater

The TCM and electricmotor are serviceable as an assembly only. Do not attempt to open or carry out internal repairs on the TCM and electric motor.