The transfer case motor is a bi-directional, permanent magnet, D.C. motor. Depending on the command received, the transfer case motor can be energized through either the motor control A or motor control B circuit. The ground circuit for the motor is provided by the motor control circuit that is not energized. The motor, through a series of gears, rotates a shaft which moves the range forks to shift the transfer case between the 2HI, 4HI, 4LO, and Neutral ranges.

A low battery condition or charging system that is faulty could produce this fault. Refer to Battery Inspection/Test and Charging System Test .

Schematic Reference

Transfer Case Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Transfer Case Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, with a scan tool command both the motor control A circuit ON and OFF. You should here the encoder motor shifting the transfer case.
2. If the vehicle passes the Circuit/System Verification, then refer to Testing for Intermittent Conditions and Poor Connections .

1. Ignition OFF, disconnect the transfer case shift control module electrical connectors C1 and C2.
2. Verify that a test lamp illuminates between B+ and C1, terminal 1.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Verify that a test lamp illuminates between B+ and C1, terminal 9.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

4. Verify that a test lamp illuminates between C1 terminal 8, and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

5. Ignition ON, verify that a test lamp illuminates between C2 terminal 10 and ground.

⇒	If the test lamp does not illuminate test the ignition 1 voltage circuit for a short to ground.

6. Ignition OFF, disconnect the transfer case encoder motor electrical connector.
7. Verify that a test lamp illuminate between B+ and terminal E of the transfer case encoder motor electrical connector.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

8. Ignition OFF, connect C1 and C2 to the transfer case shift control module.
9. Connect a DMM between terminals B and C of the transfer case encoder motor electrical connector.
10. Ignition ON, with a scan tool, command the motor control A circuit ON and OFF. The DMM should display B+ and zero voltage when commanded ON and OFF.

⇒	If the DMM displays less than B+ when commanded ON, test both circuits for a short to ground or an open/high resistance. If both circuits test normal, replace the transfer case shift control module.

11. Ignition OFF, remove the transfer case encoder motor. Inspect the shift detent lever shaft for a binding condition.

⇒	If the shift detent lever shaft inspection is normal, replace the transfer case encoder motor.

1. Ignition OFF, disconnect the transfer case shift control module electrical connector.
2. With a DMM, measure for 2-100 ohms between motor control A and motor control B terminals on the encoder motor.

⇒	If not with in the specified range, replace the transfer case encoder motor.

3. Ignition OFF, with a DMM, test for continuity between motor control A terminal and ground, an also motor control B terminal and ground, on the transfer case encoder motor.

⇒	If continuity is detected, replace the transfer case encoder motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.