Circuit Description
At each power up the transfer case shift control module runs a self test on the following:
| • | EEPROM Checksum |
| • | ROM Checksum |
| • | RAM Checksum |
| • | RAM Malfunction |
Conditions for Running the DTC
| • | Critical operational parameters stored in EEPROM have failed Checksum test indicating invalid data. |
| • | Masked ROM code has failed Checksum test indicating that masked ROM data is no longer valid. |
| • | ROM code has failed Checksum test indicating that ROM data is no longer valid. |
| • | One or more ROM locations have failed operational test indicating that some portions of RAM are not functional. |
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present and a momentary loss of battery power at the battery positive voltage circuit (CKT 40).
Diagnostic Aids
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Check the transfer case shift control module for DTCs. The transfer case shift control module is not a class 2 device. DTCs are displayed on the transfer case shift control switch. Use the following four steps to obtain
DTCs.
Did you perform A Diagnostic System Check - Transfer Case? | -- | Go to Step 2 | Go to Diagnostic System Check |
Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Did you complete the replacement? | -- | Go to Step 3 | -- | |
3 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
