Circuit Description
The transfer case shift control module controls the Transfer Case Lock Solenoid.
The lock is energized (locking action released, grounding the Lock Control Circuit) during gear shifts and in AUTO 4WD mode of operation. When power or ground is removed from the lock solenoid, (locking action applied), the transfer case motor is prevented from moving. In this manner, the system is capable of providing a 4H and 4L lock-up without the need of additional vehicle power to hold the transfer case in these positions.
This DTC detects an open lock control circuit or an open Lock feed.
Conditions for Setting the DTC
| • | The system will try to turn the lock solenoid off by opening the ground circuit. |
| • | If the module is unable to de-energize the solenoid, the system will not attempt to de-energize the solenoid again during that ignition cycle. |
| • | Transfer Case Lock output reads back as a low voltage when a high voltage is expected. |
Action Taken When the DTC Sets
| • | All shifting will be disabled. |
| • | The SERVICE 4WD indicator will be latched on for the remainder of the current ignition cycle. |
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 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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Measures for proper voltage on the lock feed circuit.
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Measures the resistance through the lock control solenoid.
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Measures for a short to ground in the transfer case lock solenoid.
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Tests the Transfer Case Lock circuit for a short to ground.
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Tests the Transfer Case Lock circuit for an open.
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Repairs the Brake Feed circuit for an open.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | Go to |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 7 | |
Measure the resistance across the encoder motor lock control using a Digital Multimeter DMM. Is the resistance reading within the specified value? | 18-25 ohms | Go to Step 4 | Go to Step 8 | |
At the transfer case side of the 4 pin connector, with a DMM measure the transfer case lock circuit for a short to ground. Was a short to ground found? | - | Go to Step 8 | Go to Step 5 | |
Was the condition found and corrected? | -- | Go to Step 10 | Go to Step 6 | |
Test the Transfer Case Lock circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 10 | Go to Step 9 | |
Check the lock feed and lock solenoid control circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 10 | Go to Step 9 | |
8 | Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement . Is the repair complete? | -- | Go to Step 10 | -- |
9 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the repair complete? | -- | Go to Step 10 | -- |
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
