Circuit Description
A normal function of the transmission control module (TCM) is to perform an internal test that verifies that the TCM EEPROM has been flashed with diagnostic and shift calibrations. The TCM also verifies that the vehicle-specific application has been locked out from changes. When the TCM detects the absence of software or an unlocked TCM, DTC P0602 sets. DTC P0602 is a type B DTC.
Conditions For Running The DTC
Condition 1:
The ignition is ON.
Condition 2:
The ignition is OFF.
Conditions For Setting The DTC
Condition 1:
The TCM EEPROM checksum is incorrect.
Condition 2:
The TCM is unable to write to the EEPROM.
Action Taken When the DTC Sets
| • | The TCM flashes the sport mode lamp and sends a MIL request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL. |
| • | The ECM records the operating conditions in the Freeze Frame at the time of the MIL request from the TCM. |
| • | The transmission operates in the default mode (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts). |
Conditions For Clearing the MIL/DTC
| • | The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL request. |
| • | A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic. |
| • | The scan tool clears the MIL/DTC. |
| • | The TCM cancels the DTC default mode actions when the ignition switch is Off long enough in order to power down the TCM. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission ? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission | |
Important: Record the Failure Records before clearing the DTCs. Using the Clear Info function erases the Failure Records from the ECM and the TCM. Did DTC P0602 reset? | -- | Go to Diagnostic Aids | ||
3 |
Caution: When you are performing service on or near the SIR components or the SIR wiring, you must disable the SIR system. Refer to Disabling the SIR System. Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs. Perform the Transmission Control Module Replacement procedure. Is the action complete? | -- | -- | |
4 | Perform the following procedure in order to verify the repair:
Did DTC P0602 reset? | -- | System OK |
