GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Safari - 4WD 🢒 Driveline/Axle 🢒 Transfer Case 🢒 DTC C0374 General System Malfunction

Circuit Description

The transfer case shift control module senses rear to front slip, a difference of rear to front propshaft speed, attempts to correct the difference by turning on the motor to apply torque to the front wheels.

Conditions for Setting the DTC

The transfer case shift control module is unable to correct sensed slip for 10 consecutive seconds. This DTC may set in conjunction with DTC C0305.

Action Taken When the DTC Sets
    • All clutch activation (slip control) will be disabled.
    • The SERVICE indicator (AWD/4WD) lamp will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC
    • Current DTC
        The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
    • History DTC
       - Once 100 consecutive ignition cycles without a fault present.
       - A scan tool CLEAR CODES command.

Diagnostic Aids

An intermittent problem may be caused by a poor connection, break in the wire insulation exposing the internal wire, or a wire that is broken inside the insulation.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Helps determine if the DTC set due to a mechanical or an electrical fault.

    2.

  2. Tests the integrity of the Motor Feed circuit.

    3.

  3. Determines whether the transfer case clutch pack is holding.

DTC C0374 General System Malfunction

Step

Action

Value(s)

Yes

No

1

Important:: If DTC C0300 or C0305 is also present perform the diagnostic for these DTCs before continuing.

Was the Transfer Case Diagnostic System Check performed?

--

Go to Step 2

Go to Transfer Case Diagnostic System Check

2

  1. Place the transmission in PARK
  2. Turn the ignition ON, with the engine OFF.
  3. Install a scan tool.
  4. Use the scan tool in order to command the Encoder Motor B ON.

Is the Encoder Motor turning ON (buzzing noise)?

--

Go to Step 4

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the encoder motor harness.
  3. Turn the ignition ON, with the engine OFF.
  4. Use the scan tool to check for DTCs.

Did DTC C0310 set?

--

Go to Step 6

Go to Step 7

4

  1. Remove the encoder motor assembly. Refer to Motor/Encoder Replacement .
  2. Connect a wrench to the transfer case sector shaft.
  3. Turn the sector shaft to apply the clutch pack.
  4. While the clutch pack is applied, attempt to turn the front propshaft using a small pry bar between the U-Joint.

Does the clutch pack hold the

--

Go to Step 6

Go to Step 5

5

Remove the transfer case and overhaul.

Is the repair complete?

--

Go to Step 8

--

6

Replace the transfer case encoder motor. Refer to Motor/Encoder Replacement .

Is the repair complete?

--

Go to Step 8

--

7

Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .

Is the repair complete?

--

Go to Step 8

--

8
  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 reset?

--

Go to Step 2

System OK