Circuit Description
The indicator lamps circuit consists of three individual lamps contained inside their respective buttons making up the transfer case shift control switch assembly. They are the 2HI, 4HI and 4LO lamps. When the ignition switch is placed in the RUN position, current is provided to the switch assembly. The transfer case shift control module provides a ground for the lamps when a particular gear is active or when the transfer case is in transition. Through solid state circuity located inside the switch assembly voltage can be regulated to provide less illumination when the headlamps or parking lights are turned ON.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step helps to determine intermittent conditions.
-
This step helps to determine if the transfer case range changes with the press of all of the transfer case shift control switch buttons.
-
This step determines if there is a faulty lamp inside the transfer case shift control switch assembly.
-
This step repairs an open in the suspect indicator control circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform A Diagnostic System Check - Transfer Case? | -- | Go to Step 2 | |
Do the transfer case shift control switch indicator lamps illuminate with the press of all of the shift control switch buttons? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Determine if the transfer case range changes with the press of all of the shift control switch buttons Does the transfer case range change with the press of all of the shift control switch buttons? | -- | Go to Step 4 | ||
Do the transfer case shift control switch indicator lamps turn ON when their specific control circuit is jumped to ground? | -- | Go to Step 5 | Go to Step 6 | |
Repair an open in the suspect control circuit(s). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 8 | Go to Step 7 | |
6 | Replace the transfer case shift control switch. Refer to Transfer Case Shift Control Switch Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
7 | Replace the transfer case control module. Refer to Transfer Case Shift Control Module Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
8 | Operate the vehicle within the conditions for causing the symptom as specified in the supporting text. Does the symptom re-occur? | -- | Go to Step 2 | System OK |
