For 1990-2009 cars

### Circuit Description

The Powertrain Control Module (PCM) is the control center of the fuel injection system. The PCM receives the information from the various sensors, and controls the systems that affect the vehicle performance. The PCM also performs the diagnostic function of the system. The PCM can recognize the operational problems, alert the driver through the malfunction indicator lamp (MIL) (Check Engine), and store a DTCs which identify the problem areas in order to aid you in making repairs. An electrically erasable programmable read only memory (EEPROM) houses the program information and the calibrations required for the engine, the transmission, and the powertrain diagnostics operation. The programming of the EEPROM can be updated by reprogramming the PCM.

### Conditions for Setting the DTC

The PCM is improperly programmed.

### Action Taken When the DTC Sets

• | The PCM will record operating conditions at the time during which the diagnostic fails. This information will store in the Failure Records buffer.

• | A history DTC stores.

### Conditions for Clearing the MIL/DTC

• | A history DTC will clear after 40 consecutive warm up cycles without a fault.

• | A scan tool can clear the MIL/DTCs.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored on the scan tool for later reference.

2. Refer to the latest Techline information for programming procedures.

3. Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.

#### DTC P0602-PCM Not Programmed

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Was the PCM just replaced? | -- | Go to Step 3 | Go to Step 4
3 |

1. Reprogram the PCM.
2. If the DTC resets, attempt to reprogram again (3 times maximum).

Does the DTC reset?

--

Go to Step 4

Go to Step 5

4 | Replace the PCM. Is the action complete? | -- | Go to Step 5 | --
5 |

1. Using the scan tool, clear the DTC's.
2. Start the engine and idle at normal operating temperature.
3. Operate the vehicle within the conditions for setting this diagnostic as specified in the supporting text.

Does the scan tool indicate that this diagnostic has ran and passed?

--

Go to Step 6

Go to Step 2

6 | Check if any additional DTC's are set. Are any DTC's displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK