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 |
• | Relay Malfunction |
• | 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 not valid. |
• | ROM code has failed Checksum test indicating that ROM data is not valid. |
• | One or more ROM locations have failed operational test indicating that some portions of RAM are not functional. |
• | Motor circuit test has indicated that one of the modules's relays is not able to make contact. |
The SERVICE indicator (4WD/AWD) lamp will be latched on and the system will be disabled.
• | Replace the transfer case shift control module. |
• | Perform the Diagnostic System Check- Transfer Case. |
The numbers below refer to the step numbers on the diagnostic table
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | |||
1 | Did you perform the Transfer Case Diagnostic System Check? | Go to Step 2 | |
Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the repair complete? | System OK | -- |