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

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

1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when this DTC set. The scan tool stores this data for later reference.

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

3. Reprogram the replacement PCM and the perform the crankshaft position system variation learn procedure. Refer to the latest Techline procedures for PCM reprogramming and Crankshaft Position System Variation Learn for the crankshaft position system variation learn procedure.

#### DTC P0602-PCM Not Programmed

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | 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 the PCM again (3 times maximum).

Does the DTC reset?

--

Go to Step 4

Go to Step 5

4 |

1. Turn OFF the ignition switch.
2. Replace the PCM. Refer to the Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 5

--

5 |

1. Using the scan tool, clear the DTCs.
2. Start the engine.
3. Idle the engine at the normal operating temperature.
4. Operate the vehicle within the conditions for running this DTC 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 to see if any additional DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to applicable DTC table | System OK