Circuit Description
This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM). This diagnostic also addresses if the ECM is not programmed.
DTC Descriptors
This diagnostic procedure supports the following DTCs.
| • | DTC P0601 Control Module Read Only Memory (ROM) |
| • | DTC P0602 Control Module Not Programmed |
| • | DTC P0604 Control Module Random Access Memory (RAM) |
| • | DTC P0606 Control Module Internal Performance |
Conditions for Running the DTC
DTC P0601
The checksum calculation at power down in the last drive cycle completely finished. DTC P0601 runs once an ignition cycle.
DTC P0602
The ignition is ON, with the engine OFF. DTC P0602 runs continuously.
DTC P0604
The read/write test at power down in the last drive cycle completely finished. DTC P0604 runs once an ignition cycle.
DTC P0606
DTC P0606 runs continuously with ignition ON or engine operating.
Conditions for Setting DTC
DTC P0601
The ECM detects the incorrect read only memory (ROM) checksum for more than 30 seconds.
DTC P0602
The ECM detects that programming is incomplete for more than 1 second.
DTC P0604
The ECM detects random access memory (RAM) errors for more than 5 seconds.
DTC P0606
The ECM detects an internal condition for more than 5 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | For an intermittent condition, refer to Intermittent Conditions . |
| • | For complete details on programming the ECM, refer to Service Programming System (SPS) in Programming. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
A DTC P0602 indicates the ECM is not programmed.
-
Attempt to program the ECM. If the ECM fails to program a second time, replace the ECM.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Does DTC P0601 or P0604 fail this ignition? | Go to Step 8 | Go to Step 3 |
Is DTC P0602 set? | Go to Step 4 | Go to Step 6 | |
4 | Program the engine control module (ECM). Refer to Service Programming System (SPS) in Programming. Does DTC P0602 reset? | Go to Step 5 | Go to Step 9 |
Does DTC P0602 reset? | Go to Step 8 | Go to Step 9 | |
6 | Is DTC P0606 set? | Go to Step 7 | -- |
7 |
Did DTC P0606 fail this ignition? | Go to Step 8 | Go to Diagnostic Aids |
8 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 9 | -- |
9 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 10 |
10 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK |
