Circuit Description
This symptom is usually the result of actions expected to take place during the transition of a transfer case mode change which has not happened. When the transfer case changes from 2WD to 4WD for example, the front axle is locked by the transfer case shift control module. If the transfer case shift control module does not sense that the front axle is applied, it waits for the action to take place before the gear change is made. While waiting, the mode switch lamp continues to flash for a period of time, and all other mode requests are ignored for the duration of the ignition cycle.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines the position of the front axle switch.
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This step helps determine if the front axle does not engage.
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This step helps determine if the front axle does not disengage.
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 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the scan tool display the Front Axle Switch status as Locked? | Go to Step 4 | Go to Step 3 | |
Using the scan tool, observe the mode that is currently selected. Is the mode switch indicator illuminated steadily in Auto 4WD, 4WD HI, or 4WD Low mode? | Go to Step 5 | ||
Using the scan tool, observe the Encoder Gear Position status. Is the transfer case in 2WD mode? | Go to Step 5 | ||
5 | Replace the transfer case shift control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the repair? | Go to Step 6 | -- |
6 |
Is the symptom still present? | Go to Step 2 | System OK |
