DIAGNOSTIC RESPONSE:
Lock in Neutral
CIRCUIT DESCRIPTION:
At power up and after clearing DTC, the Transmission Control Module (TCM) performs a self-test to determine if the calibration in memory is valid.
CONDITIONS FOR RUNNING THE DTC:
This test will run before any TCM functions.
CONDITIONS FOR SETTING THE DTC:
DTC P0602 sets if the TCM determines the present calibration is invalid.
ACTION TAKEN WHEN THE DTC SETS:
1. The CHECK TRANS light illuminates.
2. DTC is stored in the TCM history.
3. The TCM returns to the boot program, and then waits to be recalibrated.
4. The TCM inhibits shifts to range.
CONDITIONS FOR CLEARING THE DTC:
TCM must be recalibrated.
DIAGNOSTIC AIDS:
Loss of communication with TCM during recalibration corrupts the current calibration and causes this code. Reconnect using OEM TCM Reflash and calibrate TCM. Recalibrating TCM clears all DTC history.
Indication of corrupted or no calibration in TCM include:
1. Not able to connect to TCM with the diagnostic tool.
2. Cat-eyes in shift selector windows.
3. Mode light ON.
4. Blank selector windows occur after pressing any selector button.
5. Check that the TCM is getting battery power, battery grounds, and ignition sense signal.
Review applicable information in the OEM Technician Library, General Troubleshooting of Performance Complaints – Shift Selector Issues, Control System and Transmission Specifications, and other related information.
