For 1990-2009 cars

### Description

This diagnostic applies to internal microprocessor integrity conditions within the control module. This diagnostic also addresses if the control module is not programmed. The following DTCs are diagnosed in this DTC table:

• | DTC P0601 Control Module Read Only Memory (ROM)

• | DTC P0602 Control Module Not Programmed

• | DTC P1621 Control Module Long Term Memory Performance

### Diagnostic Aids

For complete details on programming the PCM, refer to Powertrain Control Module Programming .

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. A DTC P0602 indicates the PCM is not programmed.

2. Attempt to program the PCM. If the PCM fails to program a second time, replace the PCM.

#### DTC P0601-P0607, P1600, or P1621

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 | Is DTC P0602 set? | Go to Step 3 | Go to Step 5
3 | Program the PCM. Refer to Powertrain Control Module Programming . Does DTC P0602 reset? | Go to Step 4 | Go to Step 6
4 |

1. Ensure that all tool connections are secure.
2. Ensure the programming equipment is operating correctly.
3. Ensure the correct software/calibration package is used.
4. Attempt to program the PCM. Refer to Powertrain Control Module Programming .

Does DTC P0602 reset?

Go to Step 5

Go to Step 6

5 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 6 | --
6 |

1. Use a scan tool in order to clear the DTCs.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 7

Go to Step 3

7 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | Go to Diagnostic Trouble Code (DTC) List | System OK