B2725

DTC B2725

Circuit Description
The range/mode switch circuit consists of 4 normally open switches. The transfer case shift control module supplies a regulated 8 volts DC to the switch through the 8-volt reference circuit. The current travel through a 9.09 kOhms resistor located inside the switch. Then returns current 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. If no buttons are pressed, and the transfer case shift control module detects a voltage level outside the possible range approximately -0.5 to +1.0 volts for longer than 5 minutes, the transfer case shift control module will set this DTC or if a button is held down or sticks for a period longer than 5 minutes.

When each of the switches is depressed they will complete a circuit through their own specific resistor. The transfer case shift control module continuously monitors the switch input to determine whether the 4HI, AUTO 4WD, 2HI, and 4LO button selections are made by the driver. Neutral may be obtained if these conditions are met:
^ The engine is running.
^ The automatic transmission is in Neutral or the clutch pedal is depressed on a manual transmission application.
^ The vehicle speed is below 5 km/h (3 mph).
^ The transfer case is in the 2HI mode.

Once these conditions have been met, pressing and holding both the 2HI and 4LO buttons for 10 seconds will shift the transfer case into Neutral, turning on the red Neutral indicator lamp.

DTC Descriptor
This diagnostic procedure supports this DTC:
DTC B2725 ATC Mode Switch Circuit Malfunction

Conditions for Running the DTC
^ The ignition is ON.
^ The system voltage is 9 - 16 volts.

Conditions for Setting the DTC
^ The system constantly monitors the voltage on the switch signal circuit.
^ If the system detects a voltage level outside the possible range produced when no buttons are depressed, approximately -0.5 to +1.0 volts, 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 no longer exists.
^ A history DTC clears after 100 consecutive ignition cycles without a fault present.
^ History DTCs can be cleared using a scan tool.

Test Description

Steps 1-6:

Steps 7-13:

These numbers correspond 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 for proper voltage supply to the transfer case mode select switch.
4. This step tests the transfer case mode select switch for proper resistance values in all switch states.
5. This step tests the switch signal circuit for a short to voltage.
6. This step tests the switch signal circuit for an open or a short to ground.
7. This step tests the switch signal circuit for a short to the 8 volt Reg circuit.
8. This step determines whether the 8 volt Reg circuit is greater than or less than the specified voltage.
9. This step tests the 8 volt Reg circuit for a short to voltage.
10. This step tests the 8 volt Reg circuit for a short to ground.