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Home >> GMC >> 2021 >> Terrain Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 91 (Automatic Transmission - 9T45 (M3U) Or 9T50 (M3D M3H) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0707, P0708, P2802, P2803, or P2805 >> Circuit/System Description

Circuit/System Description

WARNING: This page is about a different car, the 2020 GMC Terrain and 2020 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.

For an overview of the component/system, refer to: Electronic Component Description

Circuit Description
5 V Reference Regulated voltage supplied by the control module. @ K20 Engine Control Module
Signal 1 - Terminal 2 @ B15 Transmission Internal Mode Switch The control module input circuit has an internal resistance connected to 5 V. @ K71 Transmission Control Module
Signal 2 - Terminal 4 @ B15 Transmission Internal Mode Switch The control module input circuit has an internal resistance connected to 5 V. @ K20 Engine Control Module
Low Reference Grounded through the control module. @ K20 Engine Control Module
Component Description
B15 Transmission Internal Mode Switch The hall-effect sensor has 2 separate PWM signal circuits. The transmission gear selected determines the duty cycle of the PWM signal.
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.
K71 Transmission Control Module The control module contains a microprocessor used to process input data to control outputs. The control module receives information from a variety of sensors, switches and serial data information from other control modules. This information is used to control a combination of solenoid valves to obtain the correct line pressure, gear ratio and torque converter clutch operation.

The control module K71 uses the information from the sensor signal 1 to determine what transmission gear range the vehicle operator selected.

The control module K20 uses the information from the sensor signal 2 to determine if the transmission is in neutral or park to enable the starter.