Neutral Mode Power Flow

WARNING: This page is about a different car, the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.

Shifting to the neutral position, the high/low range sleeve is centered between the input shaft and the high/low planetary carrier. The high/low range sleeve is not engaged with either the input shaft or the high/low planetary carrier teeth. The planetary differential is in the 4HI mode.

View the list of major electrical components that make up the full time four wheel drive transfer case (FT4WD) system below.

Service 4WD Indicator: The SERVICE 4WD indicator is an integral part of the cluster and cannot be serviced separately. This indicator is used to inform the driver of the vehicle of malfunctions within the FT4WD transfer case system. The SERVICE 4WD indicator is controlled by the transfer case shift control module via a Class 2 message.

Transfer Case Encoder: The encoder is mounted to the transfer case encoder motor assembly and is replaced only as an assembly. The encoder converts the shift detent lever shaft position, representing a mode/range into electrical signal inputs to the transfer case shift control module. The module detects what position the transfer case is in by monitoring the 4 encoder channels, P, B, A, and C. These inputs translate into 4HI, 4LO Lock, and Neutral, or whether the motor is still in transition between gears. The transfer case encoder channel circuits may be monitored using a scan tool.

Transfer Case Encoder Motor: The transfer case encoder motor consists of a permanent magnet (PM) DC motor and gear reduction assembly. It is located on the left hand side of the transfer case. When activated, it turns the shift detent lever shaft of the transfer case clockwise or counterclockwise, to shift the transfer case by moving the shift forks and collar assemblies inside the transfer case. The encoder motor is controlled through a 12 volt circuit provided by the transfer case shift control module. This circuit consists of a driver on both the Motor Control A and Motor Control B circuits. The encoder motor is bi-directional to allow the motor to shift the transfer case from 4HI to NEUTRAL and 4LO Lock positions. Both the motor control drivers and motor control return drivers can be turned on using a scan tool. You may also monitor Motor Control A and B circuits using a scan tool.

Transfer Case Shift Control Module: The transfer case shift control module monitors vehicle speed via the Class 2 date bus from the powertrain control module as well as controlling the operation of the transfer case encoder motor assembly.