Before Programming a Control Module

WARNING: This page is about a different car, the 2002 GMC C3500 HD and 2002 Chevrolet C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

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 customers 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 Owners manual.
  - Heating, ventilation, and air conditioning (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.
- RS-232
- The connection at the data link connector (DLC) is secure.
- 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.