Circuit Description
A normal function of the transmission control module (TCM) programming is to perform an internal check that verifies the integrity of the random access memory (RAM) allocations.
The DTC P0601 sets when the RAM is not operating correctly when checked on initialization. An area of RAM is a failed read/write test.
Conditions for Setting the DTC
| • | The EEPROM checksum test is separated in 2 independent parts, the code checksum test and the calibration checksum test. For each area the checksum is calculated and compared with the corresponding checksum valve. If the valves are different, the fault will be set. |
| • | The system voltage is too high or too low. |
| • | The transaxle input voltage is too high or too low. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The TCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer. |
| • | Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control. |
| • | After ignition OFF/ON: 3rd gear by hydraulic control. Possible P, R, and N also possible. |
| • | Power supply cut off to the PCS valve. |
Conditions for Clearing the MIL/DTC
| • | A MIL will turn OFF when the malfunction has not occurred after 3 ignition cycles. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Using a scan tool can clear history DTCs. |
Diagnostic Aids
When DTC P0601 sets, the possible cause of the fault could be the TCM.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Automatic Transmission? | Go to Step 2 | |
2 |
Does the scan tool display DTC P0601? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Is the action complete? | Go to Step 4 | -- |
4 |
Does the scan tool indicate that this diagnostic has run and passed? | Go to Step 5 | Go to Step 2 |
5 | Check if any DTCs are set. Are any DTCs displayed that have not been diagnosed? | System OK |
