Circuit/System Testing
1. Key OFF. Disconnect the X1 connector at the transfer case shift control switch (TCSCS). Install EL-49742 - harness.
Note: When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616 - GM
terminal test kit. Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.
2. Key ON (Ignition C), engine OFF.
3. Using the L-BU probes J 35616-64B, test for 4.86-5.25 V between the 5-volt reference circuit, TCSCS X1 pin 11, and the ground terminal of
EL-49742 - harness, black terminal.
锟斤拷 If the voltage is less than the specified value, test the 5-volt reference circuit for an open/high resistance or short to ground condition. If all
circuits and connections test normal, test the TCCM for proper operation.
锟斤拷 If the voltage is greater than the specified value, test the 5-volt reference circuit for a short to voltage. If all circuits and connections test
normal, test the TCCM for proper operation.
4. Using the L-BU probes J 35616-64B, test for 4.86-5.25 V between the 5-volt reference circuit, TCSCS X1 pin 11, and the switch signal circuit
TCSCS X1 pin 12.
锟斤拷 If the voltage is less than the specified value, test the switch signal circuit for an open/high resistance, short to ground or short together. If
all circuits and connections test normal, test the TCCM for proper operation.
锟斤拷 If the voltage is greater than the specified value, test the switch signal circuit for a short to voltage. If all circuits and connections test
normal, test the TCCM for proper operation.
5. Using the L-BU probes J 35616-64B, test for greater than 500 ohm between the 5-volt reference circuit, TCSCS X1 pin 11, and all other pins
of the TCSCS X1.
锟斤拷 If the resistance is less than the specified value, test the affected circuits for short together condition. If all circuits and connections test
normal, test the TCCM for proper operation.
6. Using the L-BU probes J 35616-64B, test for greater than 500 ohm between the switch signal circuit TCSCS X1 pin 12, and all other pins of
the TCSCS X1.
锟斤拷 If the resistance is less than the specified value, test the affected circuits for short together condition. If all circuits and connections test
normal, test the TCCM for proper operation.
7. Test the TCSCS for proper operation.
Component Testing
TCSCS - Mode Switch Circuit
1. Key OFF. Remove the TCSCS.
2. Using the L-BU probes J 35616-65, measure the resistance for each of the mode positions of the TCSCS between the 5-volt reference circuit,
TCSCS X1 pin 11, and the switch signal circuit TCSCS X1 pin 12.
锟斤拷 If the resistance is outside the specified ranges, replace the TCSCS.
3. Test the TCCM for proper operation.
TCCM - Mode Switch Circuit
1. Key ON, engine OFF. Install the TCSCS.
2. Using the Data Display feature of the scan tool, monitor the Mode Switch Supply and Return Voltages while turning the TCSCS through each
mode.
锟斤拷 If the voltage is less than the specified value, test the affected circuit for an open/high resistance, short to ground or short together. If all
circuits and connections test normal, reprogram the TCCM. If the DTC resets replace the TCCM.
锟斤拷 If the voltage is greater than the specified value, test the affected circuit for a short to voltage. If all circuits and connections test normal,
reprogram the TCCM. If the DTC resets replace the TCCM.
3. Perform the Circuit/System Testing.
