These diagnostic procedures will help you to find and repair Automatic Transfer Case (ATC) system malfunctions. This service category also contains information for repairing ATC system malfunctions. For best results, use the diagnostic tables, and follow the sequence listed below:
- Perform the Transfer Case Diagnostic System Check. All ATC diagnostics must begin with the Transfer Case Diagnostic System Check. The Transfer Case Diagnostic System Check determines the following:
- Refer to the diagnostic table as directed by the Transfer Case Diagnostic System Check. The diagnostic tables will help enable you to diagnose any ATC system malfunction. Bypassing these procedures may result in the following:
- Repeat the Transfer Case Diagnostic System Check after you perform any repair or diagnostic procedures. This will verify that you correctly performed the repair. This will also ensure that no other malfunctions exist.
| • | Proper SERVICE AWD/4WD lamp operation |
| • | Ability of the transfer case shift control module to communicate through the Data Link Connector (DLC) |
| • | Existence of ATC Diagnostic Trouble Codes (DTC) |
| • | Extended Diagnostic Time |
| • | Incorrect Diagnosis |
| • | Incorrect Parts Replacement |
Circuit Description
The ignition switch supplies Ignition 3 voltage to the transfer case shift control module at connector C1 terminal E10 using the 4WD Fuse. When the ignition switch is first turned to the RUN position, the shift control module responds by flashing the SERVICE AWD/4WD lamp for approximately 2 seconds, then turning it OFF, while performing tests on the ATC system. The shift control module will continue to perform tests on the ATC system during a normal drive cycle.
Diagnostic Aids
You must diagnose the diagnostic trouble codes in the order specified by the Transfer Case Diagnostic System Check. Failure to do so may result in the following:
| • | Extended Diagnostic Time |
| • | Incorrect Diagnosis |
| • | Incorrect Parts Replacement |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
This test checks for proper operation of the serial data line.
-
This test will identify the stored diagnostic trouble codes and whether or not they are current or history.
-
The SERVICE indicator (AWD/4WD) lamp should turn off after approximately 2 seconds.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Did the SERVICE indicator (AWD/4WD) lamp turn ON? | -- | Go to Step 2 | Go to Transfer Case Mechanical Symptom Table |
Does the scan tool communicate with the module? | -- | Go to Step 3 | Go to Data Link Connector System Check in Wiring Systems | |
Request for ATC diagnostic trouble codes (DTCs) display. Are there any Current DTCs present in the module? | -- | Go to Step 4 | ||
4 | Are there any History DTCs present? | -- | Go to Step 9 | Go to Step 5 |
Did the SERVICE indicator (AWD/4WD) lamp turn ON and turn OFF after approximately 2 seconds? | -- | Go to Step 6 | ||
6 | Was the vehicle brought in for a performance concern? | -- | Go to Powertrain OBD System Check | Go to Step 7 |
7 |
Were there any ATC DTCs present? | -- | Go to Step 8 | |
8 | Were there any mechanical problems identified on the road test? | -- | Go to the Transfer Case Mechanical Symptom Diagnosis | System OK |
9 |
Were there any ATC DTCs present? | -- | Go to Diagnostic Trouble Codes | Go to Step 10 |
10 | Refer to Diagnostic Aids for the recorded History DTC. Are the repairs complete? | -- | Go to Step 1 | -- |
