GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Astro - 4WD 🢒 DTC 🢒 DTC C0376

Circuit Description

The front and rear propshaft speed sensor is a permanent magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and number of pulses increases as speed increases. The module converts the pulsating AC voltage to a propshaft RPM which is used for calculations. The propshaft RPM can be displayed with a scan tool.

This DTC detects greater than 10 percent difference in the speed sensor inputs.

Conditions for Running the DTC
    • The ignition is ON.
    • The system voltage is 9-16 volts.
    • The transmission is not in Park/Neutral.
    • The engine is running.
    • The front axle is engaged.
    • The front propshaft indicates speed less than 75 mph.

Conditions for Setting the DTC

The transfer case shift control module detects continued readings of front and rear propshaft speed signal which do not match. The module is unable to determine propshaft speed.

The system logs the DTC if the front and rear propshaft inputs indicates a speed greater than 10% difference for 40 seconds.

Action Taken When the DTC Sets
    • The SERVICE AWD indicator remains illuminated for the remainder of the current ignition cycle.
    • All clutch activation, slip control 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 number(s) below refer to the step number(s) on the diagnostic table.

  1. This step determines if DTCs C0300 or C0305 have set.

    2.

  2. This step helps determine if the transfer case speed sensors are working properly.

    3.

  3. This step tests to see if the DTC will reset.

    4.

  4. This step inspects for mismatches and whether speed sensors are wired correctly.

    5.

  5. This step inspects the transfer case for mechanical failures.

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

1

Did you perform the Diagnostic System Check - Transfer Case?

Go to Step 2

Go to Diagnostic System Check - Transfer Case

2

Has the transfer case shift control module set C0300 or C0305 as a current DTC?

Go to DTC C0300 or DTC C0305

Go to Step 3

3
  1. Clear all ATC DTCs.
  2. Place the transfer case into 4WD mode.
  3. Connect a scan tool.
  4. With the scan tool observe the value of the front and rear propshaft speed data parameters in the transfer case data list while driving.

Are both propshaft speed sensors within 10 percent of each other?

Go to Step 4

Go to Step 5

4

Does DTC C0376 reset?

Go to Step 7

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

5
  1. Turn the ignition OFF.
  2. Inspect the following for a mismatch:
    3. • Front and rear axle ratios
    • All tires
    • Front or rear propshaft missing
  3. Inspect that the speed sensors are wired correctly by comparing vehicle wire harness to the system schematics. Inspect the connectors for proper connection and for loose terminals.

Was a problem found and corrected?

Go to Step 8

Go to Step 6

6

Inspect the transfer case for a mechanical failure. Refer to Transfer Case Disassemble in Unit Repair.

Has a mechanical failure been identified and repaired?

Go to Step 8

Go to Step 7

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