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
| • | The ignition is ON. |
| • | The 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.
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This step determines if two or more of the 5 volt encoder signal circuits are shorted together.
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This step tests for proper voltage on the four encoder signal circuits.
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This step tests for a short to voltage, open or high resistance on the encoder low reference circuit.
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This step determines which encoder signal circuits are shorted together.
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This step determines if any of the encoder signal circuits have an open or high resistance condition.
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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? | -- | Go to Step 2 | |
Do more than one of the four encoder channels indicate OFF when each encoder channel circuit is individually shorted to ground? | -- | Go to Step 5 | Go to Step 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 | |
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? | -- | Go to Step 11 | Go to Step 7 | |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 | |
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? | -- | Go to Step 11 | Go to Step 10 | |
Did the shift detent lever shaft bind? | -- | 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? | -- | Go to Step 11 | -- |
9 | Replace the encoder motor. Refer to Transfer Case Encoder Motor Replacement . Did you complete the repair? | -- | Go to Step 11 | -- |
10 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Did you complete the repair? | -- | Go to Step 11 | -- |
11 |
Does the DTC set? | -- | Go to Step 1 | System OK |
