Circuit Description
The transfer case motor is a bi-directional, permanent magnet, DC motor. When energized through motor control A or motor control B, the ground is provided by the opposing motor control circuit, then grounded through the transfer case shift control module ground circuit The motor, through a series of gears, rotates a shaft which moves the mode and range forks to shift the transfer case between 4H, AUTO 4WD, 2H, N, and 4L ranges. While the transfer case motor is energized, the transfer case shift control module also energizes the solenoid for the transfer case lock. The motor lock is disabled, locking action released, and free turning of the transfer case motor and sector shaft is then allowed.
This symptom indicates a short to ground, short to power, or high resistance in the motor control A, motor control B, or lock solenoid control circuits.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for an open or high resistance in the motor windings.
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This step tests for an open or high resistance in the lock solenoid windings.
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This step determines if the module is sending voltage through the motor control A circuit.
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This step determines if the module is sending voltage through the motor control B circuit.
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This step determines if the reason voltage is not getting from the transfer case shift control module to the encoder motor through motor control A and B circuits is due to an open or high resistance in these circuits.
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This step determines if the proper 8 volt reference signal is coming from the transfer case shift control module.
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This step determines if the module is producing the correct voltage through the P, A, B, and C channels.
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This step tests the encoder signal ground circuit for an open or high resistance.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics Connector End View Reference: Transfer Case Control Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Transfer Case? | -- | Go to Step 2 | |
Is the resistance within the specified values? | 0.8-25 ohms | Go to Step 3 | Go to Step 10 | |
Using a DMM, measure the resistance of the transfer case lock solenoid by probing the lock solenoid control circuit and the battery positive voltage circuit. Is the resistance within the specified values? | 18-25 ohms | Go to Step 4 | Go to Step 10 | |
Is battery voltage present? | -- | Go to Step 5 | Go to Step 6 | |
Was battery voltage present? | -- | Go to Step 7 | Go to Step 6 | |
Test motor control A or motor control B circuits for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | - | Go to Step 12 | Go to Step 11 | |
Was the voltage within the specified range? | 7-9 V | Go to Step 8 | Go to Step 9 | |
Measure the voltage on the encoder signals P, A, B, and C on the module side of the harness. Are they within the specified values? | 4.8-5.1 V | Go to Step 9 | Go to Step 11 | |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | |
10 | Replace the motor encoder. Refer to Transfer Case Motor/Encoder Replacement . Did you complete the repair? | -- | Go to Step 12 | -- |
11 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Did you complete the repair? | -- | Go to Step 12 | -- |
12 |
Is the symptom still present? | -- | Go to Step 2 | System OK |
