GM Service Manual Online
For 1990-2009 cars only

Object Number: 159242  Size: SH

Circuit Description

The PCM used in this vehicle utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). The EEPROM contains program information and the calibrations required for engine, Transaxle, and Powertrain diagnostics operation.

Unlike the PROM used in past applications, the EEPROM is not replaceable. When the PCM is replaced or a calibration update is required, the PCM must be programmed using scan tool or approved Techline equipment. Refer to PCM Replacement/Programming.

Conditions for Setting the DTC

The PCM does not contain the correct program required to operate the vehicle.

Action Taken When the DTC Sets

    • The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic runs and fails.
    • If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control and illuminate the TRACTION OFF lamp.
    • The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

    • The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
    • The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool.

Diagnostic Aids

DTC P0602 indicates that the PCM was not programmed. If the PCM can not be programmed the only possible repair is PCM replacement. Remember to program the replacement PCM with the correct software and calibration for the vehicle. Refer to PCM Replacement/Programming.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain OBD System Check performed?

--

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

2

  1. Program the PCM with correct software. Refer to On-Vehicle Service in Powertrain Control Module and Sensors for procedures.
  2. Retest for DTC P0602.

Did DTC P0602 set?

--

Go to Step 3

Repair complete

3

Replace the PCM.

Important: :  Replacement PCM must be programmed. Refer to PCM Replacement/Programming .

Is the action complete?

--

Go to A Powertrain On Board Diagnostic (OBD) System Check

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