Circuit Description

WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.

This symptom indicates that the transfer case encoder motor circuits are not functioning properly. This symptom is similar to DTC 003 but differs because the counter inside the transfer case control module (TCCM) has not yet set DTC 003. One of the following conditions may exist.

One of the internal power relays in the TCCM is not energizing or de-energizing.
An open exists in the Battery Positive Voltage, Ground, Motor Control A or Motor Control B circuits.
A short to ground exists in the Battery Positive Voltage, Motor Control A or Motor Control B circuits.
A short exists within the motor or TCCM.

The transfer case encoder motor has a bi-directional permanent magnet, D.C. motor. When a shift request is made by the TCCM voltage will be applied through one of the motor control circuits and the TCCM will provide the ground through the other motor control circuit. When a shift is requested in the opposite direction, the TCCM will reverse polarity on these two circuits. The motor through a series of gears, rotates a shaft which moves the mode and range forks to shift the transfer case between gears.