Diagnostic Trouble Codes
The Transfer Case Diagnostic System Check must always be the starting
point of any system diagnosis. The Transfer Case Diagnostic System Check verifies
proper SERVICE indicator (AWD/4WD) lamp operation and checks for ATC diagnostic
trouble codes (DTC) using the scan tool. The following describes the difference
between current and history DTCs:
| • | Current DTCs - Malfunctions that are presently being detected.
Random access memory (RAM) stores the current DTCs. Turning the ignition switch
to the OFF position resets current DTCs and logs the codes in history.
The presence of a current DTC will cause the transfer case shift control
module to turn ON the SERVICE indicator (AWD/4WD) lamp. |
| • | History DTCs - All malfunctions detected since last clearing
of history memory. Electrically erasable programmable read only memory (EEPROM)
stores the history DTCs. A scan tool clear codes command will erase history
DTCs. |
Use of Special Tools
You should be familiar with the tools in this service category listed
under the heading Special Tools. You should know how to measure voltage and
resistance. Diagnosis requires proper use of the following tools:
| • | The J 35616
Connector
Test Adapter Kit |
