Circuit/System Testing

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.