GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls and Fuel - 7.8L (LF8) 🢒 DTC P0601, P0602, P0603, P0604, P0605, P0606, or P062F

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0602: Control Module Not Programmed

DTC P0606: Control Module Internal Performance

DTC P062F: Control Module Long Term Memory Performance

Circuit/System Description

These DTCs apply to internal microprocessor integrity conditions within the engine control module (ECM). This diagnostic also addresses if the ECM is not programmed. The ECM monitors its ability to read and write to the memory. It also monitors a timing function.

Conditions for Running

P0602

The ignition is ON.

P062F

    • The battery voltage is between 10-16 volts.
    • The ignition is ON for longer than 2 seconds.

Conditions for Setting

P0602

The ECM detects a malfunction in its internal EEPROM.

P0606

The ECM detects that the ECM internal main CPU malfunction or ECM internal monitoring IC malfunction.

P062F

The ECM detects that the calculated checksum does not agree with the ECM internal registered checksum.

Action Taken When the DTC Sets

DTCs P0602, P0606, and P062F are Type A DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0602, P0606, and P062F are Type A DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Component Views
    •  Engine Control Module Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

Verify the integrity of the ECM power supply or ground circuit by inspecting for the following conditions:

    • Damaged components
    • Loose or improper installation

Circuit/System Testing

Important: You must perform Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Test the voltage and ground circuits to the control module for the following:
    2. • A short
    • An open
    • High resistance
  2. Observe the DTCs with the scan tool.
    3. ⇒If DTC P0602 or P062F is set, attempt to program the ECM before replacing the ECM. Refer to Service Programming System (SPS) .
    ⇒If DTC P0606 was set while performing SPS Programming, clear the DTCs and exit the diagnostic.
  3. Replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module (ECM) replacement, setup, and programming