Circuit Description
The transfer case encoder is a switch that converts a shaft position, representing a mode or range position, into electrical signals for use by the transfer case shift control module. The encoder houses 4 hall effect sensors that are used for channels P, A, B, and C. These sensors provide a path to ground, when a magnet, (part of the shift rail), passes over them.
The transfer case shift control module supplies an 8 V reference and a ground circuit for the encoder hall effect sensors to function via CKT 431 and 1554 respectfully.
The transfer case shift control module supplies 5 V on all of the channels, thus as these channels are pulled to ground, the module can interpret the location of the transfer case shift position.
This DTC detects an open, short to ground, or a short to voltage (12 V) in CKT 431, an open in CKT 1554, an open, short to ground, or short to voltage (12 V) in the encoder channel CKTS 1555, 1557, 1558, or 1556.
Conditions for Setting the DTC
The transfer case shift control module reads back all high or low voltage on the encoder channel circuits.
Action Taken When the DTC Sets
| • | All motor activity will stop and the transfer case lock engaged. |
| • | A default rail to rail shift may be allowed, (toggle between 4H and 2H). |
| • | The SERVICE indicator (AWD/4WD) lamp 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 number(s) below refer to the step number(s) on the diagnostic table.
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This test will help to isolate whether or not the fault exits in the transfer case motor encoder.
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This test will determine if the suspect encoder circuit is shorted to ground.
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This test will help determine if one or more encoder channels are shorted together.
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This test will determine if the suspect encoder circuit is open.
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This test determines if CKT 431 is shorted to power.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | |
Do all circuits display OFF? | -- | Go to Step 5 | Go to Step 3 | |
Is the resistance reading less than the specified value? | OL | Go to Step 4 | Go to Step 21 | |
4 | Repair short to ground in the suspect circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
5 |
Is the voltage within the specified values? | 7-9 V | Go to Step 6 | Go to Step 13 |
Does more than one Encoder Circuit display ON simultaneously? | -- | Go to Step 10 | Go to Step 7 | |
7 | Do all the circuits display ON when their individual circuit is jumpered to terminal A? | -- | Go to Step 11 | Go to Step 8 |
Is the resistance reading across the suspect circuit within the specified values? | 0-2 ohms | Go to Step 21 | Go to Step 9 | |
9 | Repair the open in the suspect circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
10 | Repair a shorted condition between the circuits that were simultaneously turning ON in Step 6. Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 22 | -- |
11 | Use a J 39200 DMM to measure voltage between transfer case encoder harness connector C2 terminals F, B, D and C to terminal A. Is the voltage within the specified values? | 4.8-5.1 V | Go to Step 12 | Go to Step 21 |
12 | Replace transfer case encoder. Refer to Motor/Encoder Replacement . Is the action complete? | -- | Go to Step 22 | -- |
13 | Was the voltage reading previously measured in step 7 greater than 9 volts? | -- | Go to Step 14 | Go to Step 15 |
Is the voltage reading within the specified values? | 0 V | Go to Step 21 | Go to Step 17 | |
15 | Use a J 39200 DMM to measure resistance from transfer case encoder harness connector C2 terminal A to ground. Is the resistance reading within the specified values? | 0-2 ohms | Go to Step 16 | Go to Step 18 |
16 |
Is the resistance reading within the specified values? | 0-2 ohms | Go to Step 22 | Go to Step 20 |
17 | Repair short to voltage in CKT 431. Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 22 | -- |
18 |
Is the resistance reading within the specified values? | 0-2 ohms | Go to Step 21 | Go to Step 19 |
19 | Repair open in CKT 1554. Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 22 | -- |
20 | Repair open in CKT 431. Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 22 | -- |
21 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the action complete? | -- | Go to Step 22 | -- |
22 |
Have all the ATC components been reconnected and properly mounted? | -- | Go to Step 23 | -- |
23 | Clear all the ATC DTCs. Have all the ATC DTCs been cleared? | -- | -- |
