The 4HI indicator circuit consists of an LED dimming supply circuit and a 4HI indicator control circuit. When the 4HI mode is selected, current is supplied to the 4HI indicator by the LED dimming supply circuit, traveling through the 4HI indicator LEDs, at which time the transfer case shift control module supplies the ground through the 4HI indicator control circuit.
This diagnostic procedure supports the following DTC:
DTC B0775 Four Wheel Drive High Range (4HI) Indicator Circuit Malfunction
• | The ignition is ON. |
• | System voltage is 9-18 volts. |
• | The system monitors the voltage on the 4HI indicator control circuit. |
• | If the system detects a voltage of 3 volts or less for 1.5 seconds when the 4HI indicator is not commanded, the DTC is logged. |
• | If the system detects a voltage of 4.5 volts or greater when the 4HI indicator is commanded, the DTC is logged. |
The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
• | The transfer case shift control module clears the DTC if the condition for setting the DTC is not currently present. |
• | A history DTC clears after 100 consecutive ignition cycles without a fault present. |
• | History DTCs can be cleared using a scan tool. |
The numbers below refer to the step numbers on the diagnostic table.
This step looks for the visual operation of the 4HI indicator. Command both the ON and OFF states.
This step helps determine if proper voltage is supplied to the transfer case select switch.
This step helps determine if there is a short to ground in the indicator control circuit.
This step helps determine if there is an open in the indicator control circuit.
This step tests the indicator feed circuit for an open or high resistance.
This step tests the 4HI neutral control circuit for a short to ground.
This step tests the 4HI neutral control circuit for an open or high resistance.
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: Transfer Case Control Schematics Connector End View Reference: Transfer Case Control Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Does the 4HI neutral turn ON and OFF with each command? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
With a scan tool, command the AWD, 4LO, and 2HI indicators ON and OFF. Do all the indicators turn ON and OFF? | Go to Step 4 | Go to Step 6 | |
Does the 4HI indicator stay ON? | Go to Step 7 | Go to Step 5 | |
Does the 4HI indicator illuminate? | Go to Step 8 | Go to Step 9 | |
Test the LED dimming supply circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 9 | |
Test the 4HI indicator control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 10 | |
Test the 4HI indicator control circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 10 | |
9 | Replace the transfer case select switch. Refer to Transfer Case Shift Control Switch Replacement . Did you complete the repair? | Go to Step 11 | -- |
10 |
Important : After transfer case shift control module replacement and reprogramming, ensure all doors are closed and the key is out of the ignition, then open and close the doors again and wait 2 minutes to avoid incomplete programming or false communication DTCs. Replace the transfer case shift control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the repair? | Go to Step 11 | -- |
11 |
Does the DTC set? | Go to Step 2 | System OK |