GM Service Manual Online
For 1990-2009 cars only
Makes šŸ¢’ Chevrolet šŸ¢’ 2001 šŸ¢’ Chevy K Silverado - 4WD šŸ¢’ Driveline/Axle šŸ¢’ Transfer Case - NVG 261-NP2 (Two Speed Manual) šŸ¢’ Powertrain Control Module Replacement

Service of the powertrain control module (PCM) should consist of either replacement of the PCM or electrically erasable programmable read only memory (EEPROM) programming. If diagnostic procedures call for PCM replacement, inspect the replacement PCM to ensure that the correct part PCM is being used.

Important: 

   ā€¢ To prevent internal PCM damage, the ignition must be OFF when disconnecting or reconnecting power to the PCM. For example, when working with a battery cable, PCM pigtail, PCM fuse, or jumper cables.
   ā€¢ Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM module connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
   ā€¢ The replacement PCM will not be programmed. DTC P0601 and P0602 indicate the EEPROM is not programmed or has malfunctioned. The following MUST be performed anytime the PCM is replaced:
   ā€¢ Programming of the EEPROM
   ā€¢ The PCM Password Learn procedure.
   ā€¢ The Idle Learn Procedure .
   ā€¢ The Crankshaft Position System Variation Learn Procedure .
   ā€¢ Resetting the engine oil life monitor .
   ā€¢ The Functional Check
   ā€¢ The following must be performed anytime the PCM is disconnected, loses power, or is reprogrammed:
   ā€¢ The Idle Learn Procedure .
   ā€¢ The Functional Check

Removal Procedure

    Important: It is necessary to record the remaining engine oil life. If the replacement module is not programed with the remaining engine oil life, the engine oil life will default to 100%. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 5000 km (3,000 mi) from the last engine oil change.

  1. Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.

    2. Object Number: 334905 Size: MH
  2. Release the PCM cover mounting holes (1, 5) away from the mounting tabs on the PCM mounting bracket.
  3. Release the PCM cover (8) from the mounting bracket.
  4. Remove the PCM cover.

    5. Notice: Do not touch the connector pins or soldered components on the circuit board in order to prevent possible electrostatic discharge (ESD) damage to the PCM.

    Notice: In order to prevent internal damage to the PCM, the ignition must be OFF when disconnecting or reconnecting the PCM connector.

  5. Disconnect the PCM harness connectors (6).
  6. Release the spring latch (2) from the PCM.
  7. Release the PCM mounting tabs (3) from the PCM.
  8. Remove the PCM (4) from the engine compartment.

Installation Procedure

    Object Number: 334905 Size: MH
  1. Install the PCM (4) to the PCM mounting bracket (7) ensuring that the mounting tabs (3) are engaged.
  2. Secure the spring latch (2) to the PCM.

    3. Notice: Refer to Fastener Notice in the Preface section.

  3. Connect the PCM connectors (6) to the PCM (4).

    4. Tighten
    Tighten the PCM connector end fasteners to 8 NĀ·m (70 lb in).

  4. Install the PCM cover (8) to the PCM mounting bracket (7), ensuring the mounting tabs on the PCM mounting bracket are engaged into the mounting holes in the PCM cover.
  5. If a new PCM is being installed, program the PCM. Refer to Powertrain Control Module Programming .