The Speed Calibration Programming must be done when any of the following procedures are performed:
| • | The control module is replaced. |
| • | The tire size is changed. |
| • | The gear ratio is changed. |
If the control module is being replaced, the Speed Calibration information must be retrieved before replacing the control module. Perform the Retrieving Speed Calibration Information from the Control Module and the Speed Calibration Programming During
Control Module Programming procedures listed below.
If the control module is not being replaced, a shorter procedure can be used to perform Speed Calibration Programming. Perform the Speed Calibration Programming without Control Module Programming procedure listed below.
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 customers concern. If the control module is being replaced the Speed Calibration also be programmed.
Ensure the following conditions are met before programming a control module:
| - | 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. |
| • | Daytime running lights (DRL)--Applying the parking brake, on most vehicles, disables the DRL system. Refer to the Owners Manual. |
| • | 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) 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. |
Retrieving Speed Calibration Information from the Control Module
Important: Only perform this procedure if the control module is being replaced or the axle ratio or tire size has been changed. The current Axle Ratio and Tire Revolutions Per Mile can be determined with the Tech 2®.
The Axle Ratio can also be found on the Service Parts Identification (SPID) and the Tire Revolutions Per Mile can be obtained from the tire manufacturer as follows:
- Turn OFF the ignition.
- Install the Tech 2® to the data link connector (DLC).
- Turn ON the ignition, with the engine OFF.
- Turn OFF all vehicle accessories.
- Select Diagnostics.
- Select Powertrain.
- Finish identifying the vehicle configuration as requested by the Tech 2®.
- Identify the vehicle configuration as requested by the Tech 2®.
- Select Special Functions.
- Select Engine Output Controls.
- Select Speed Reprogramming.
- Select Read Speed Calibration.
- Record the Axle Ratio and Tire Revolutions Per Mile.
Speed Calibration Programming without Control Module Programming
- Install the Tech 2® to the DLC.
- Turn ON the Tech 2®.
- Turn ON the ignition, with the engine OFF.
Important: DO NOT go into Service Programming Systems at this point.
- Select Diagnostics.
- Select the correct model year of the vehicle.
- Select Medium Duty Truck.
- Select Powertrain.
- Select the correct engine size.
- Select the correct transmission for the vehicle.
- Select Special Functions.
- Select Engine Output Controls.
- Select Speed Reprogramming.
- Select Reprogram Speed Calibration.
- Select Done to continue.
- Enter the axle ratio using the F0 through F9 keys on the Tech 2® key pad.
- Select Done.
- Enter the tire revolutions per mile using the F0 through F9 keys on the Tech 2® key pad. This information can be obtained from the tire supplier.
- Select Done.
- At this point, all entered information can be verified. Select Previous and the input information can be changed.
- If the information entered is correct, select reprogram and the Tech 2® will indicate Reprogram Successful.
- Select Restart if the Speed Calibration still needs to be changed. The axle ratio and tire revolutions per mile can be re-entered without reconnecting to the Techline® terminal.
- Turn OFF the ignition and allow the control module to power down. This time should be at least 30 seconds. The Tech 2 may beep when the control module stops communicating.
- Start the vehicle and test drive.
Speed Calibration Programming During Control Module Programming
- Select Service Programming with the Tech 2®.
- Select Request Info.
- Identify the vehicle information as requested by the Tech 2®.
- Select Continue.
- Verify the displayed VIN with the vehicle VIN. If the displayed VIN does not match the actual VIN, write down the actual VIN and correct the VIN at the Techline® terminal.
- When complete, Exit Service Programming.
- Turn OFF the Tech 2® and disconnect the Tech 2® from the vehicle.
- Turn OFF the ignition.
- Connect the Tech 2® to the Techline® terminal.
- Select the Service Programming System at the main screen.
- Highlight the following information on the Select Diagnostic Tool and Programming Process Screen:
| • | Select Diagnostic Tool--Select Tech 2 |
| • | Select Programming Process--Identify whether an existing module is being reprogrammed or a module is being replaced with a new one. |
| • | Select ECU Location--Select vehicle |
- Select Next.
- Verify the VIN connections and select Next.
- Select the appropriate controller for the vehicle being serviced.
- Select Speed Calibration.
- Select Normal.
- After the download is complete, turn OFF the Tech 2®.
- Disconnect the Tech 2® from the Techline® terminal.
- Install the Tech 2® to the DLC.
- Turn ON the Tech 2®.
- Turn ON the ignition, with the engine OFF.
Important: DO NOT go into Service Programming Systems at this point.
- Select Diagnostics.
- Select the correct model year of the vehicle.
- Select Medium Duty Truck.
- Select Powertrain.
- Select the correct engine size.
- Select the correct transmission for the vehicle.
- Select Special Functions.
- Select Engine Output Controls.
- Select Speed Reprogramming.
- Select Reprogram Speed Calibration.
Important: This procedure will allow the user to change the speed calibration for the vehicle. This procedure should only be done when a new control module has been installed or when the axle ratio or tire size has been changed.
- Select Done to continue.
- Enter the axle ratio using the F0 through F9 keys on the Tech 2® key pad.
- Select Done.
- Enter the tire revolutions per mile using the F0 through F9 keys on the Tech 2® key pad. This information can also be obtained from the tire supplier or tire manufacturer.
- Select Done.
- At this point, all entered information can be verified. Select Previous and the input information can be changed.
- If the information entered is correct, select reprogram and the Tech 2® will indicate Reprogram Successful.
- Select Restart if the Speed Calibration still needs to be changed. The axle ratio and tire revolutions per mile can be re-entered without reconnecting to the Techline® terminal.
- Turn OFF the ignition and allow the control module to power down. This time should be at least 30 seconds. The Tech 2 may beep when the control module stops communicating.
- Start the vehicle and test drive.
