GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls - 6.6L (LLY) 🢒 High Idle Switch Programming

Before Programming a Control Module

Important: DO NOT program a control module unless you are directed by a service procedure or you are directed by a General Motors Corporation service bulletin. Programming a control module at any other time will not permanently correct a customer's concern.

Ensure the following conditions are met before programming a control module:

    • Vehicle system voltage
       - There is no charging system concern. All charging system concerns must be repaired before programming a control module.
       - Battery voltage is greater than 12 volts but less than 16 volts. The battery must be charged before programming the control module if the battery voltage is low.
       - A battery charger is NOT connected to the vehicle's battery. Incorrect system voltage or voltage fluctuations from a battery charger, may cause programming failure or control module damage.
       - Turn OFF or disable any system that may put a load on the vehicle's battery.
   • Twilight sentinel
   • Interior lights
   • Daytime running lights (DRL)--Applying the parking brake, on most vehicles, disables the DRL system. Refer to the Owner's Manual.
   • HVAC systems
   • Engine cooling fans, etc.
    • The ignition switch is in the proper position. The scan tool prompts you to turn ON the ignition, with the engine OFF. DO NOT change the position of the ignition switch during the programming procedure, unless instructed to do so.
    • All tool connections are secure.
       - The connection at the data link connector (DLC)
       - Voltage supply circuits
    • DO NOT disturb the tool harnesses while programming. If an interruption occurs during the programming procedure, programming failure or control module damage may occur.

High Idle Switch Programming
  1. Turn ON the ignition.
  2. Select Diagnostics with the Tech 2®.
  3. Identify the vehicle information as requested by the Tech 2®.
  4. Select Powertrain.
  5. Select the engine and transmission application.
  6. Select Special Functions.
  7. Select PTO Options.
  8. Select the Change Options softkey.
  9. Select High Idle.
  10. Highlight Standby Speed.
  11. Increase or Decrease the parameter to the desired value using the softkeys.
  12. Select the Reprogram softkey.

    13. Important: The ECM will not operate under the new value until the it has powered down once.

  13. Turn OFF the ignition until communication with the ECM is lost, as indicated on the scan tool.
  14. Start the vehicle and confirm the new settings by operating the high idle switch.