The transfer case shift control module is equipped with the ability to store diagnostic information which is useful to a technician in the event of a module, component or wiring failure. This information can be retrieved from the transfer case shift control module by way of flash codes which are displayed on the three transfer case shift control switch buttons. These buttons are located on the instrument panel to the right of the steering wheel. The following steps provide an easy way of retrieving the flash codes properly in the event that a failure has occurred.

1. Turn OFF the ignition for 10 seconds.
2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
3. Turn ON the ignition, with the engine OFF.
4. Observe the transfer case shift control switch select buttons for flashing codes. Refer to Diagnostic Trouble Code (DTC) List

Note: If the transfer case shift control switch buttons all blink only once and then stop, no fault codes are stored in the transfer case shift control module. When one DTC is stored into memory, that code will blink (the number of times they blink indicate the code number) followed by a three second pause and then repeat. If more than one code is stored, the first code will blink, followed by a three second pause and then the second code will blink. This sequence will continue until PIN 13 on the (DLC) is no longer grounded.