GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Blazer - 4WD 🢒 Restraints 🢒 SIR 🢒 DTC C0324

Circuit Description

The transfer case shift control module controls the transfer case lock solenoid. The lock is energized, locking action released by grounding the lock control circuit, during gear shifts and in AUTO 4WD mode of operation. When voltage or ground is removed from the lock solenoid, locking action applied, releasing the ground on the lock control circuit, the transfer case motor is prevented from moving. The system is capable of providing a 4H and 4L lock-up without the need of additional vehicle power to hold the transfer case in these positions.

This DTC detects a shorted lock solenoid coil, or the lock control circuit shorted to 12 volts.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0324 T-Case Lock Circuit High

Conditions for Running the DTC
    • The ignition is ON.
    • The system voltage is 9-16 volts.

Conditions for Setting the DTC

Transfer case lock output reads back as a high voltage when a low voltage is expected.

Action Taken When the DTC Sets
    • The system tries to turn the lock solenoid on, grounding the lock control circuit. If unable to energize the solenoid, the system does not attempt to energize the solenoid again during that ignition cycle.
    • The SERVICE 4WD indicator remains illuminated for the remainder of current ignition cycle.
    • All shifting is disabled.

Conditions for Clearing the DTC
    • The transfer case shift control module clears the DTC if the condition for setting the DTC no longer exists.
    • A history DTC clears after 100 consecutive ignition cycles without a fault present.
    • History DTCs can be cleared using a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step measures the resistance across the encoder motor brake.

    2.

  2. This step tests the transfer case lock circuit for a short to voltage.

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 - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn the ignition OFF.
  2. Disconnect the motor encoder.
  3. Turn the ignition ON, with the engine OFF.
  4. Using a DMM, measure the resistance across the encoder motor lock control.

Is the resistance reading within the specified range?

20-80 ohms

Go to Step 3

Go to Step 5

3

  1. Turn the ignition OFF.
  2. Disconnect the transfer case shift control module.
  3. With the encoder motor still disconnected, turn the ignition ON, with the engine OFF.
  4. Using a test lamp that is connected to a good ground, probe the transfer case lock solenoid control circuit of the encoder motor lock control.

Does the test lamp illuminate?

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Go to Step 4

Go to Step 6

4

Repair the transfer case lock solenoid control circuit for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 7

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5

Replace the motor encoder. Refer to Transfer Case Motor/Encoder Replacement .

Did you complete the repair?

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Go to Step 7

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6

Replace the transfer case shift control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the repair?

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Go to Step 7

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7
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC set?

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Go to Step 2

System OK