Circuit Description
The range/mode switch circuit consists of 4 modes. The transfer case shift control module supplies 5 volts to the switch through the 5 volt reference circuit. The current travel through the resistor of the currently active mode. The current is then returned to the transfer case shift control module through the switch signal circuit.
The transfer case shift control module constantly monitors this signal voltage to determine the condition of the mode switch circuit.
When each of the modes are selected they complete a circuit through their own specific resistor. The transfer case shift control module continuously monitors the switch input to determine whether the Neutral, 2HI, 4HI, or 4LO mode was selected by the driver.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2725 ATC Mode Switch Circuit Malfunction
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The system voltage is 9-18 volts. |
Conditions for Setting the DTC
| • | The system constantly monitors the voltage on switch signal circuit. |
| • | If the system detects a voltage level under 0.35 volt or greater than 0.70 volt for 60 seconds, the DTC is logged. |
Action Taken When the DTC Sets
| • | All shifting is disabled. |
| • | The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle. |
Conditions for Clearing the DTC
| • | The transfer case shift control module will clear the current DTC if the condition for setting the DTC is not currently present. |
| • | 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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This step tests for proper operation of the transfer case mode select switch.
-
This step tests the mode switch for proper resistance values in all mode switch states.
-
This step tests the switch signal wire for a short to ground, short to voltage, or high resistance
Step | Action | Values | 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 - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the scan tool indicate that the modes are in the correct state while pressing the mode buttons? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Does the DMM indicate all resistance values within the specified ranges? | Normal: 8,635-9,544 ohms 4 HI: 630-696 ohms 2 HI: 1,440-1,592 ohms Neutral: 974-1,035 ohms 4 LO: 2,228-2,462 ohms | Go to Step 4 | Go to Step 5 | |
Test the switch signal and 5 volt reference circuits for a short to voltage, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 6 | |
5 | Replace the mode switch. Refer to Transfer Case Shift Control Switch Replacement . Did you complete the repair? | -- | Go to Step 7 | -- |
6 | Replace the transfer case shift control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the repair? | -- | Go to Step 7 | -- |
7 |
Does the DTC set? | -- | Go to Step 2 | System OK |
