For 1990-2009 cars only
Circuit Description
This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM).
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0601 Control Module Read Only Memory (ROM) |
| • | DTC P0604 Control Module Random Access Memory (RAM) |
| • | DTC P0605 Control Module Programming Read Only Memory (ROM) |
Conditions for Running the DTC
DTC P0601
| • | The ignition is ON, with the engine OFF or the engine is operating. |
| • | DTC P0601 runs once an ignition cycle. |
DTC P0604
| • | The ignition is ON, with the engine OFF or the engine is operating. |
| • | DTC P0604 runs once an ignition cycle. |
DTC P0605
| • | The ignition is ON, with the engine OFF or the engine is operating. |
| • | DTC P0605 runs once an ignition cycle. |
Conditions for Setting DTC
DTC P0601
The ECM detects that the checksum calculation does not match the expected checksum.
DTC P0604
The ECM detects an internal condition for more than 3 seconds.
DTC P0605
The ECM detects an internal condition for more than 3 seconds.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will store conditions which were present when the DTC was set as Failure Records data only. |
| • | This information will not be stored in the Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | The DTC clears when the diagnostic runs and passes. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |
2 | Replace the engine control module (ECM). Refer to Engine Control Module Replacement. Did you complete the replacement? | Go to Step 3 | -- |
3 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 4 |
4 | Are there any DTCs that have not been diagnosed? | System OK |
