Circuit Description
The transfer case encoder motor is a permanent magnet DC motor and gear reduction assembly. The encoder motor is controlled with a pulse width modulated (PWM) circuit within the transfer case shift control module.This circuit consists of a power supply relay (motor control A) circuit that supplies voltage to the motor. The motor control B circuit is a PWM driver that varies the duty cycle to control the amount of current through the motor to ground.
This DTC detects a short to ground on the motor control A circuit or the motor control B circuit.
Conditions for Setting the DTC
| • | The system will test the motor circuits by checking for unwanted voltage. |
| • | The system supplies voltage on the motor control A circuit and reads the voltage back on the motor control B circuit. |
| • | The transfer case shift control module senses a low voltage return on the motor control A circuit or the motor control B circuit when a high voltage is expected. |
| • | If the system detects a problem with the circuits, the DTC is logged. |
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 does not exist. |
| • | A history DTC will clear 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.
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Tests the motor circuit for a current malfunction.
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Tests motor control A for an open or short to ground.
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Tests motor control B for an open or short to ground.
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Tests for continuity across the motor windings.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Did you perform the Transfer Case Diagnostic System Check? | -- | Go to Step 2 | |
Does the Encoder Motor turn ON and OFF? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Important: The transfer case motor control circuits have capacitors connected between their circuit and ground. if making resistance checks with a DMM, allow the reading to stabilize, approximately 10 seconds, before making the final measurement. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 4 | |
|
Important: The transfer case motor control circuits have capacitors connected between their circuit and ground. if making resistance checks with a DMM, allow the reading to stabilize, approximately 10 seconds, before making the final measurement. Test motor control B for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 5 | |
Test the resistance across the motor circuit. Were the resistance readings within the specified range? | 0.5-35 ohms | Go to Step 6 | Go to Step 7 | |
6 | Test the motor windings for a short to ground. Was there a short to ground in the motor windings? | -- | Go to Step 7 | Go to Step 8 |
7 | Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
8 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
