Circuit Description
The 4WD indicator lamp is located in the instrument cluster. Ignition 1 voltage is supplied to the IPC when the ignition switch is in the START or RUN position. When the vehicle is in START or RUN and the PCM receives the axle switch signal from the front axle actuator, the PCM sends a class 2 signal to the instrument cluster turning on the 4WD indicator. The 4WD indicator will stay on as long as the axle switch signal input is present.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Tests for an intermittent condition.
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Determines whether the failure is the result of a faulty front axle circuit or the instrument cluster.
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Tests for proper signal voltage to the PCM.
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Tests for proper ignition 1 voltage to the instrument cluster.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Did you perform A Diagnostic System Check - Transfer Case? | -- | Go to Step 2 | |
Verify the fault is present. Does the system operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Does the 4WD indicator turn ON? | -- | Go to Step 4 | Go to Step 5 | |
Does the voltage measure within the specified value? | 9-14 V | Go to Step 8 | Go to Step 9 | |
Test the ignition 1 voltage circuit for a proper voltage at the instrument cluster. Does the voltage measure within the specified value? | 9-14 V | Go to Step 6 | Go to Step 7 | |
6 | Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges, and Console. Did you complete the replacement? | -- | Go to Step 10 | -- |
7 | Repair an open or high resistance in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 10 | -- |
8 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.3 L, Powertrain Control Module Replacement in Engine Controls - 4.8 L, 5.3 L, and 6.0 L, or Powertrain Control Module Replacement in Engine Controls - 8.1 L. Did you complete the replacement? | -- | Go to Step 10 | -- |
9 | Inspect the axle switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. If OK, replace the front axle actuator. Refer to Electric Motor Actuator Replacement in Front Drive Axle. Did you complete the replacement? | -- | Go to Step 10 | -- |
10 | Operate the vehicle in order to determine if the symptom has been corrected. Is the symptom still present? | -- | System OK | Go to Step 2 |
