4. Using the L-BU probes J 35616-64B, connect a test light between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground.
The test light should illuminate dimly.
锟斤拷 If the test light does not illuminate, obtain a different test light and repeat step 4.
5. Key OFF. Wait 30 seconds for the TCCM to shut down.
Note: The TCCM must see the added resistance of the test light on the control circuit at key ON or the TCCM will shut the control circuit
drivers OFF. Volt meters will not work for this test.
6. Using the L-BU probes J 35616-64B, connect a test light between the TCSCS harness as specified below for the LED control circuit being
tested.
7. Key ON, engine OFF.
8. Using the Special Function ability of the scan tool, command the affected LED ON and OFF. The test light should turn OFF and ON as
commanded.
锟斤拷 If the test light remains illuminated when commanded OFF, test the affected control circuit for a short to ground. If all circuits and
connections test normal, replace the TCCM.
锟斤拷 If the test light remains OFF when commanded ON, test the affected control circuit for an open/high resistance or short to voltage. If all
circuits and connections test normal, replace the TCCM.
TCSCS
1. Using the L-BU probes J 35616-65B, connect the EL-49741 - 9 V+ power source harness to the TCSCS as specified below for the LED being
tested. Connecting the harness in the opposite pins will not illuminate the LED.
2. Connect a 9 V battery to the EL-49741 - harness.
3. Verify that only the indicator being tested illuminates.
锟斤拷 If the indicator does not illuminate when tested or the incorrect indicator illuminates, replace the TCSCS.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Transfer Case Shift Control Switch Replacement (Without SLT) (See: Powertrain Management/Transmission Control Systems/Sensors and
Switches - Transmission and Drivetrain/Sensors and Switches - Transfer Case/Four Wheel Drive Selector Switch/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for TCSCM replacement, setup, and programming
* Transfer Case High/Low Clutch Reset (See: Transmission and Drivetrain/Transfer Case/Testing and Inspection/Symptom Related Diagnostic
Procedures/MP 3023/3024-NQH - Transfer Case/Transfer Case High/Low Clutch Reset)
B0780
DTC B0780
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B0780 01
- 4WD LO Indicator Circuit Short to Battery
