B2725

DTC B2725

Circuit Description

The mode switch circuit consists of 5 modes. The transfer case shift control module supplies a regulated 5 volts, DC to the switch through the 5-volt regulator circuit. The current travels through the resistor of the currently pressed mode button. 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 will complete a circuit through their own specific resistor while the button is pressed. The transfer case shift control module continuously monitors the switch input to determine whether the Neutral, Differential Lock, 4HI, 4HI Lock, or 4LO Lock 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 0.3 volt or greater than 0.75 volts for 60 seconds, the DTC is logged.

Action Taken When the DTC Sets

* All shifting will be disabled.
* The SERVICE 4WD indicator will remain 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 33 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.
2. This step tests for proper operation of the transfer case mode select switch.
3. This step tests the mode switch for proper resistance values in all mode switch states.
4. This step tests for proper voltage on the 5-volt reference circuit.
5. This step tests the 5-volt reference circuit for an open, high resistance, short to voltage, or short to ground.
6. This step tests the switch signal circuit for an open, high resistance, short to voltage, or short to ground.

Step 1 - Step 7:

Step 8 - Step 9: