Circuit Description
The accessory switch circuit consists of 4 modes. The transfer case shift control module supplies 5 volts to the switch through the switch signal circuit. The current travels through the resistor of the currently active mode. The current on the switch signal circuit is monitored by the transfer case shift control module. The voltage on the switch signal circuit will vary depending on which mode button is pressed by the driver.
The transfer case shift control module constantly monitors the switch signal circuit to determine the condition of the accessory 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 signal circuit 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 9-16 volts. |
Conditions for Setting the DTC
| • | The system constantly monitors the voltage on 5 volt reference circuit. |
| • | If the system detects a voltage level that is out of range for 10 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. |
| • | The transfer case defaults to 4WD high mode. |
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. |
Diagnostic Aids
| • | Check the inline connector C200 for proper connection, bent pins, damage, or corrosion. Refer to Harness Routing Views and Delphi Connectors in Wiring Systems. |
| • | Check the transfer case shift control module connectors C1 and C2 for proper connection and bent or corroded pins or terminals. Refer to Repairing Connector Terminals in Wiring Systems. |
| • | Check for water leaks at doors and bulkhead areas. Refer to Waterleak Test Preparation . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests the accessory switch for proper resistance values in all accessory switch states.
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This step tests the switch signal circuit for proper voltage.
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This step tests the switch signal circuit for a short to ground, short to voltage, open, or high resistance.
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This step test the switch signal low circuit for an open, 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 DMM indicate all resistance values within the specified ranges? | 4 HI: 656.2-669.4 ohms 2 HI: 1.50-1.53 K ohms Neutral: 1.010-1.031 K ohms 4 LO: 2.32-2.36 K ohms Normal: 9.00-9.18 K ohms | Go to Step 3 | Go to Step 6 | |
Was the voltage reading within the specified values? | 4.8-5.2 V | Go to Step 5 | Go to Step 4 | |
Test the 5-volt reference circuit for a short to voltage, a short to ground, an open, or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 7 | |
Test the switch signal low circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 8 | Go to Step 7 | ||
6 | Replace the accessory switch. Refer to Accessory Switch Replacement in Instrument Panel, Gages and Console. Did you complete the repair? | -- | Go to Step 8 | -- |
7 | 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 8 | -- |
8 |
Does the DTC set? | -- | Go to Step 2 | System OK |
