GM Service Manual Online
For 1990-2009 cars only

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), also known as the Check Engine lamp , and store 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.
    • Use a scan tool to clear the DTCs.

Test Description

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

  1. Refer to the latest Techline™ information for programming procedures.

  2. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

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. Refer to Powertrain Control Module Replacement/Programming .
  2. If the DTC resets, attempt to reprogram the PCM again. Attempt this no more than 3 times.

Does the DTC reset?

--

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

  3. Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 5

--

5

  1. Use a scan tool to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK