GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Geo 🢒 1997 🢒 Metro 🢒 Engine 🢒 Engine Controls - 1.0L 🢒 DTC P0603 Control Module Long Term Memory Reset

Description

The powertrain control module (PCM) has detected a failure in the communication circuitry.

Conditions for Setting the DTC

An error was detected in the EEPROM data readout.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC
    • The MIL turns OFF after three consecutively passing trips without a fault present.
    • A History DTC clears after 40 consecutive warm-up cycles without a fault.
    • Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC.

Diagnostic Aids

Check the PCM for water contamination. Water entering the PCM can cause damage and corrosion to the circuit boards and to internal components. Repair the source of the water entry before the installation of a replacement PCM.

Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

  1. The Powertrain (OBD) System Check prompts the technician to complete some basic checks and store the Freeze Frame 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 in the scan tool for later reference.

    2.

  2. This step determines if the fault is present. Replace the PCM if this DTC sets again.

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

Important: If the vehicle does not start, crank the engine in order to allow the DTC to set.

  1. Install a scan tool.
  2. Clear the scan tool information.
  3. Turn OFF the ignition, in order to initialize the PCM.
  4. Start the engine.
  5. Road test the vehicle.

Does the scan tool indicate a DTC P0603?

--

Go to Step 3

Go to Diagnostic Aids

3

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 4

--

4
  1. Perform ther scan tool Clear DTC Information function and road test the vehicle within the Freeze Frame conditions that set the DTC.
  2. Review the scan tool data and check for DTCs. The repair is complete if no DTCs are stored.

Are any DTCs displayed on the scan tool?

--

Go to the Applicable DTC Table

System OK