Circuit/System Testing

WARNING: This page is about a different car, the 2017 GMC Yukon XL, 2017 GMC Yukon, 2017 Chevrolet Tahoe, and 2017 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, disconnect the harness connector at the S77 transfer case shift control switch.
ON, engine OFF.

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.
Testing for steps 3 - 5 is performed on the S77 transfer case shift control switch harness connector using the L-BU probes J-35616-64B.

Test for 4.75 - 5.25 V between the 5-Volt reference circuit, terminal 11 and a good ground, such as the ground terminal of the EL-49742 harness, black terminal.
- If less than the specified range
1. Ignition OFF, disconnect the X1 harness connector at the K69 transfer case control module.
2. Test for less than 10 Ω in the 5-Volt reference circuit end to end.
  - If 10 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 10 Ω
3. Test for infinite resistance between 5-Volt reference circuit terminal 11 and a good ground.
  - If less than infinite resistance, repair the short to ground in the circuit.
  - If infinite resistance
4. Test for greater than 10 Ω between the 5-Volt reference circuit terminal 11 and all other terminals of the S77 transfer case shift control switch harness connector.
  - If 10 Ω or less, repair the shorted together condition in the affected circuits.
  - If greater than 10 Ω, replace the K69 transfer case control module and perform the Range Actuator Learn procedure.
    Refer to Transfer Case Control Module Replacement , and Transfer Case High/Low Clutch Reset .
- If greater than the specified range
1. Ignition OFF, disconnect the X1 harness connector at the K69 transfer case control module. Ignition ON, Engine OFF.
2. Test for less than 1 V between the 5-Volt reference circuit terminal 11 and a good ground.
  - If 1 V or greater, repair the short to voltage in the circuit.
  - If less than 1 V
3. Test for greater than 10 Ω between the 5-Volt reference circuit, terminal 11 and all other terminals of the S77 transfer case shift control switch harness connector.
  - If 10 Ω or less, repair the shorted together condition in the affected circuits.
  - If greater than 10 Ω, replace the K69 transfer case control module and perform the Range Actuator Learn procedure.
    Refer to Transfer Case Control Module Replacement , and Transfer Case High/Low Clutch Reset .
- If within the specified range
5-Volt reference circuit and K69 transfer case control module OK.
Test for 4.75 - 5.25 V between the 5-Volt reference circuit, terminal 11, and the switch signal circuit, terminal 12.
- If less than the specified range
1. Ignition OFF, disconnect the X1 harness connector at the K69 transfer case control module.
2. Test for less than 10 Ω in the switch signal circuit end to end.
  - If 10 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 10 Ω
3. Test for infinite resistance between switch signal circuit and a good ground.
  - If less than infinite resistance, repair the short to ground in the circuit.
  - If infinite resistance
4. Test for greater than 10 Ω between the switch signal circuit, terminal 12 and all other terminals of the S77 transfer case shift control switch harness connector.
  - If 10 Ω or less, repair the shorted together condition in the affected circuits.
  - If greater than 10 Ω, replace the K69 transfer case control module and perform the Range Actuator Learn procedure.
    Refer to Transfer Case Control Module Replacement , and Transfer Case High/Low Clutch Reset .
- If greater than the specified range
1. Ignition OFF, disconnect the X1 harness connector at the K69 transfer case control module. Ignition ON, Engine OFF.
2. Test for less than 1 V between the switch signal circuit, terminal 12 and a good ground.
  - If 1 V or greater, repair the short to voltage in the circuit.
  - If less than 1 V
3. Test for greater than 10 Ω between the switch signal circuit, terminal 12 and all other terminals of the S77 transfer case shift control switch harness connector.
  - If 10 Ω or less, repair the shorted together condition in the affected circuits.
  - If greater than 10 Ω, replace the K69 transfer case control module and perform the Range Actuator Learn procedure.
    Refer to Transfer Case Control Module Replacement , and Transfer Case High/Low Clutch Reset .
- If within the specified range
Switch signal circuit and K69 transfer case control module OK.