A normal function of the transmission control module (TCM) is to perform an internal test that verifies the security of the diagnostic and shift calibration programming. The programming must contain security codes that enable a software lock to engage. The software lock is designed to prevent unauthorized changes to the diagnostics or shift calibrations. The software lock utility is processed independently from the diagnostic and shift calibration software and contains application specific data. This software lock data is entered into the TCM during the final assembly of the vehicle.
When the security codes from the diagnostic and shift calibration software fail to engage the software lock, the TCM sets DTC P0602. DTC P0602 is a type C DTC.
The ignition is ON.
The TCM detects an unlocked calibration memory range.
• | The TCM requests the ECM to illuminate the service vehicle soon (SVS) lamp. |
• | The TCM turns the Trans. Protection Mode ON. When the Trans. Protection Mode is ON, the following conditions occur: |
- | The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range. |
- | The line pressure is at maximum. |
- | The torque converter clutch (TCC) is disabled. |
- | The TCM freezes the transmission adaptive functions. |
• | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
• | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
• | The TCM stores DTC P0602 in TCM history. |
• | The TCM clears the SVS lamp request, when the condition no longer exists. |
• | A scan tool can clear the SVS Lamp/DTC. |
• | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
• | The TCM cancels the default actions when the ignition is OFF long enough in order to power down the TCM. |
DTC P0602 may set as a result of TCM reprogramming.
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 3.0L (L81) | ||||
2 |
Important:
Did DTC P0602 reset? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
Perform the Transmission Control Module Reprogramming Procedure. Refer to Service Programming System (SPS) . Did DTC P0602 reset? | -- | Go to Step 4 | Go to Step 5 | |||||
4 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the action complete? | -- | Go to Step 5 | -- | ||||
5 | Perform the following procedure in order to verify the repair:
Does the DTC reset? | -- | Go to Step 2 | Go to Step 6 | ||||
6 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.0L (L81) | System OK |