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For 1990-2009 cars only

Circuit Description

The transfer case shift control module consists of four encoder channels, which are supplied 5 volts. These four channels are P, C, A, and B, each running to a switch located inside the encoder/motor assembly. When a particular encoder channel is active, the switch is closed and 5 volts flow through the encoder signal return circuit. If the module wants to request motor position, a low side driver pulls the voltage low on the encoder signal return and the corresponding channel circuit, indicating motor position.

The transfer case shift control module supplies 5 volts on all the channels. As these channels are pulled to ground, the module can interpret the location of the transfer case shift position.

This DTC detects an open, high resistance or a short to voltage in the encoder signal return circuit, or an open, high resistance or short to voltage in the encoder channel circuits.

Conditions for Running the DTC

    • Ignition is ON.
    • System voltage is 9-18 volts.

Conditions for Setting the DTC

The transfer case shift control module reads back a high voltage when a low voltage is expected, or low voltage when a high voltage is expected on the encoder channel circuits, or the encoder signal return circuit.

Action Taken When the DTC Sets

    • All motor activity stops.
    • All the transfer case shift control switch mode indicators are commanded OFF.
    • The SERVICE 4WD indicator is latched on for the remainder of the current ignition cycle.
    • If a new mode is requested while the DTC is present, either current or history, the indicator for the mode requested flashes for 15 seconds and then goes out.

Conditions for Clearing the DTC

    • The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
    • A history DTC will clear after 33 consecutive ignition cycles without a fault present.
    • History DTCs can be cleared using a scan tool.

Diagnostic Aid

Check the mechanical condition of the shift lever detent shaft connected to the motor. If this shaft has too much mechanical play this can cause an under voltage or over voltage from the encoder causing the DTC to set.

Test Description

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

  1. This step determines if two or more of the 5 volt encoder signal circuits are shorted together.

  2. This step checks for proper voltage on the four encoder signal circuits.

  3. This step tests for a short to voltage, open or high resistance on the encoder low reference circuit.

  4. This step determines which encoder signal circuits are shorted together.

  5. This step determines if any of the encoder signal circuits have an open or high resistance condition.

  6. This step determines if a binding shift detent lever shaft is causing the DTC.

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?

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Go to Step 2

Go to Diagnostic System Check - Transfer Case

2

  1. Apply the parking brake.
  2. Raise the vehicle on a hoist.
  3. Disconnect the connector at the transfer case.
  4. Turn the ignition ON, with the engine OFF.
  5. Install a scan tool.
  6. While monitoring the encoder channels on the scan tool, short to ground each of the encoder channel circuits on the module side of the harness with a jumper wire.

Do more than one of the four encoder channels indicate OFF when each encoder channel circuit is individually shorted to ground?

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Go to Step 5

Go to Step 3

3

At the transfer case connector, test the encoder signal circuits on the module side of the harness with a DMM.

Are the voltages within the specified range?

4.3-4.7 V

Go to Step 4

Go to Step 6

4

With the ignition in the OFF position, test the encoder low reference circuit for a short to ground, short to voltage, open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 11

Go to Step 7

5

  1. Disconnect C1 and C2 from the transfer case shift control module.
  2. With a DMM, check for two or more encoder signal circuits being shorted together. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 11

Go to Step 10

6

Test the suspect circuits for a short to ground, short to voltage, open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 11

Go to Step 10

7

  1. Remove the encoder motor.
  2. Inspect the shift detent lever shaft for a binding condition. Refer to Transfer Case Encoder Motor Replacement .

Did the shift detent lever shaft bind?

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Go to Step 8

Go to Step 9

8

Remove the transfer case for disassembly and repair. Refer to Transfer Case Disassemble in Transfer Case - BW 4482-NR4 Unit Repair Manual.

Did you complete the repair?

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Go to Step 11

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9

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

Did you complete the repair?

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Go to Step 11

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10

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

Did you complete the repair?

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Go to Step 11

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11

  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 1

System OK