GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 DTC 🢒 DTC C0362

Circuit Description

The range/mode switch circuit consists of 4 normally open switches. The transfer case shift control module supplies a regulated 8 volts DC to the switch through the 8 volt reference circuit. The current travels through a 9.09 K ohms resistor located inside the switch, then returns current to the transfer case shift control module through the switch signal circuit.

When each of the switches are depressed they complete a circuit through their own specific resistor. The transfer case shift control module continuously monitors the switch input to determine whether the 4HI, AUTO 4WD, 2HI, and 4LO button selections are made by the driver. NEUTRAL may be obtained if the following conditions are met:

    • The engine is running.
    • The automatic transmission is in NEUTRAL.
    • The vehicle speed is below 5 km/h (3 mph).
    • The transfer case is in the 2HI mode.

Once these conditions have been met, pressing and holding both the 2HI and 4LO buttons for 10 seconds shifts the transfer case into NEUTRAL, turning on the red NEUTRAL indicator lamp.

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

Conditions for Setting the DTC
    • After the system turns the output ON, grounding the 4WD Low signal circuit, and reads back a high voltage, the DTC sets. The system does not attempt it again during that ignition cycle.
    • The transfer case shift control module reads back a high voltage when a low voltage is expected on the 4WD Low signal circuit.

Action Taken When the DTC Sets
    • Transmission shift points may be affected.
    • SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.

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 tests the functionality of the mode/range buttons.

    2.

  2. This step tests the ability of the modules to operate the transfer case modes.

Step

Action

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

Go to Diagnostic System Check - Transfer Case

2

  1. Install a scan tool.
  2. Start the engine.

    3. Important: NEUTRAL range will only be obtained by pressing and holding both the 2 HI and the 4 LO buttons simultaneously for 10 seconds. Refer to the Circuit Description.

  3. Place the transmission into NEUTRAL.
  4. Set the parking brake.
  5. Observe Commanded Mode Indicator States on the scan tool while depressing each of the mode/range buttons.

Does the state change with the press of any of the mode/range buttons?

Go to Step 4

Go to Step 3

3
  1. Using a scan tool, command through the ranges of the mode/range switch.
  2. With a scan tool, observe all commanded mode indicator states while shifting through the different modes.

Does the mode indicator state change?

Go to Step 4

Go to Step 5

4

Replace the transfer case shift control switch. Refer to Transfer Case Shift Control Switch Replacement .

Did you complete the replacement?

Go to Step 6

--

5

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

Did you complete the replacement?

Go to Step 6

--

6
  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?

Go to Step 2

System OK