Circuit Description
The range/mode switch circuit consists of 5 modes. The transfer case shift control module supplies 5 volts to the switch through the 5 volt reference circuit. The current travels through the resistor of the 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 4HI, AUTO 4WD, 2HI, or 4LO mode was selected.
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. |
| • | System voltage is 9-18 volts. |
Conditions for Setting the DTC
| • | The system constantly monitors the voltage on the switch signal circuit. |
| • | If the system detects a voltage level under 0.1 volt or greater than 4.9 volts for 2.5 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 clears the current DTC if the condition for setting the DTC is not currently present. |
| • | A history DTC clears 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.
-
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 | |
Does the scan tool indicate that the 4WD indicators are in the correct state? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
Does the DMM indicate all resistance values within the specified ranges? | 2 HI: 230-245 ohms AWD: 526-580 ohms 4 HI: 1,042-1,107 ohms 4 LO: 2,039-2,165 ohms Neutral: 4,467-4,743 ohms | Go to Step 4 | Go to Step 5 | |
Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 6 | |
5 | Replace the selector mode switch. Refer to Transfer Case Shift Control Switch Replacement . Did you complete the repair? | -- | Go to Step 7 | -- |
6 |
Important : After transfer case shift control module replacement and reprogramming make sure all doors are closed and the key is out of the ignition, then open and close the doors again and wait 2 minutes to avoid incomplete programming or false communication DTCs. Replace the transfer case shift control module. Refer to Control Module References 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 |
