The 4WD indicator lamp is located in the instrument cluster. Ignition 1 voltage is supplied to the instrument panel cluster (IPC) when the ignition switch is in the START or RUN position. When the vehicle is in START or RUN and the powertrain control module (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.
The numbers below refer to the step numbers on the diagnostic table.
Tests for an intermittent condition.
Determines whether the failure is the result of a faulty 4WD system.
Determines if the failure is the result of a faulty instrument cluster.
Determines if the failure is the result of a faulty PCM.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Did you perform A Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Verify the fault is present. Does the system operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
Does the front axle disengage when the 4WD control lever is in the 2WD position? | -- | Go to Step 4 | ||
Does the 4WD indicator turn OFF? | -- | Go to Step 5 | Go to Step 8 | |
Test the axle switch signal circuit for voltage at the PCM. Does the voltage measure within the specified value? | 9-14 V | Go to Step 6 | Go to Step 7 | |
6 |
Did you complete the replacement? | -- | Go to Step 9 | -- |
7 | Replace the PCM. Refer to Control Module References for replacement, set-up, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- |
8 | Replace the instrument panel cluster. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 | Operate the vehicle in order to determine if the symptom has been corrected. Is the symptom still present? | -- | System OK | Go to Step 2 |