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Home >> Chevrolet >> 2018 >> Spark LT, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 56 (Automatic Transmission - JATCO CVT) >> Diagnostic Information and Procedures >> DTC P0705, P0706 or P0851: Transmission Range Switch (MR8) >> Circuit/System Description

Circuit/System Description

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Circuit Description
Ignition Supplied from a relay thru a fuse.
Signal Regulated voltage supplied by the control module.
Signal The control module input circuit has an internal resistance connected to ground.
Ground The output of the switch is connected of chassis ground.
Component Description
B15 Transmission Internal Mode Switch A matrix of ON/Off switches used to control/indicate transmission range.
Refer to Electronic Component Description 
K71 Transmission Control Module An electronic control module used to control the transmission.
Refer to Electronic Component Description 

DTC P0705, P0706 

The transmission range switch is a sliding contact switch which is part of the B15 Transmission Internal Mode Switch assembly and is externally mounted on the transmission manual shaft. The transmission range switch is a multi-signal switch. The Ignition Main Relay in the Fuse Block - Underhood supplies ignition voltage to the transmission range switch on a Run/Crank Ignition 1 circuit. The transmission control module provides individual grounds for each of the transmission range position circuits. Each transmission shift lever position grounds one of the switch circuits. In order to determine the gear range selected by the driver, the transmission control module compares the voltage combinations on the signal circuits to a transmission range switch combination look up table stored in the TCM memory. Refer to Transmission Range Switch Logic below.

DTC P0851 

The park/neutral position switch is an ON/OFF switch which is part of the B15 Transmission Internal Mode Switch assembly and is externally mounted on the transmission manual shaft. The Engine Control Module supplies ignition voltage to the park/neutral position switch on the Park Neutral Position Switch Park Signal circuit. When in Park or Neutral the B15 Transmission Internal Mode Switch assembly provides a chassis ground for the circuit. This indicates to the engine control module that the transmission is in an acceptable gear to allow engine start up.

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