Circuit Description
The transfer case shift control module uses the VIN information for calculations that are required for the different calibrations used based on axle ratio, transmission, tire size, and engine. The system does not know which calibration to use without this information.
Conditions for Setting the DTC
The transfer case shift control module does not receive a valid VIN digit for the correct application, K truck, L van or T truck within 3 seconds after power up.
Action Taken When the DTC Sets
| • | The ignition counts since last fault will be cleared. |
| • | The system will be disabled until valid VIN data is received. |
| • | The SERVICE indicator (AWD/4WD) lamp will be latched on. |
Conditions for Clearing the DTC
A history DTC will clear after a valid VIN digit is received.
Possible Causes
Class 2 Data bus malfunction, vehicle control module (VCM) malfunction, module installed in wrong vehicle.
Diagnostic Aids
- Using a Scan Tool , check all components connected to the Class 2 serial data line.
- Inspect the vehicle control module (VCM) calibration for a miscalibrated EEPROM
- Inspect the transfer case shift control module part number for an incorrect part number
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | |
2 | Using a Scan Tool , check all the components connected to the Class 2 serial data line. Refer to Scan Tool Does Not Communicate with Class 2 Data Line in Electrical Diagnosis. Is the Class 2 serial data line communicating properly? | -- | Go to Step 3 | Go to Diagnostic System Check - Data Link Communications in Data Link Communications |
3 | Inspect the VCM EEPROM calibration. Refer to Powertrain OBD System Check. Is the VCM calibration correct? | -- | Go to Step 4 | Go to Powertrain OBD System Check |
4 | Replace the transfer shift control module with the correct part number. Have all the ATC components been reconnected and properly mounted? | -- | -- |
