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 module, component or wiring failures. 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 Before obtaining DTCs, perform the following transfer case control
module (TCCM) Self-Test.
TCCM Self-Test
- Observe the transfer case shift control switch indicators while
turning the ignition switch to RUN. A properly operating system will flash
all indicators and then will return to the current gear. If the system is
operating normally, then proceed to Displaying Codes.
- If the TCCM failed the Self-Test, then test the following
circuits.
| • | Battery Positive Voltage (40 and 1640), and Ignition 3 Voltage
for battery voltage |
| • | Ground Circuit for ground |
| • | Diagnostic enable circuit for an open or high resistance |
| • | Transfer case shift control switch connector |
- If the above circuits are normal but the TCCM still fails the
Self-Test, replace the TCCM. Refer to
Transfer Case Shift Control Module Replacement
.
DTC Displaying
- Turn OFF the ignition for 10 seconds.
- 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.
- Turn ON the ignition, with the engine OFF.
- Observe the transfer case shift control switch select buttons
for flashing codes. Refer to
Diagnostic Trouble Code (DTC) List
.
Important: 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 in memory, that code will blink that number
of times followed by a 3 second pause and then repeat. |
| • | If more than one code is stored, the first code will blink,
followed by a 3 second pause and then the second code will blink. |
| • | This sequence will continue until PIN 13 on the DLC
is no longer grounded. |
