Writing Tunes Back to the Vehicle

Before you begin, ensure that:

The vehicle has a fully charged battery. Connecting the vehicle's battery to a battery charger before writing a tune is recommended.
Your laptop has a fully charged battery.

Follow these steps to write a tune back to the vehicle:

1. Plug the interface cable into the vehicle's OBD-II port. Connect the other end to your PC's USB port. See Connecting to a Vehicle for more information.
2. If VCM Scanner is open, close it now.
3. Open VCM Editor. Ensure that a valid tune file for this vehicle is currently open.
4. Select Write Vehicle from the Flash menu.

NOTE: The first time you attempt to write to each vehicle, you will be prompted to purchase a license for that vehicle.

5. Turn the vehicle ignition to the ON (or RUN) position, but do not start the engine.

NOTE: Some vehicles require special procedures to be put in the correct state. See Putting a Vehicle in the "ON" State for more information.

6. Make sure the doors are closed and all accessories are turned off.

CAUTION: Do not use any vehicle accessories, including the door locking mechanism, during reading or writing procedures.

7. Wait 10 to 15 seconds.
8. Click the Write button.
9. Allow the PC to write the VCM until the status bar indicates the write has been completed.
10. Turn off the ignition and unplug the interface cable. Wait at least 15 seconds before restarting the vehicle.
11. The new calibration has now been written to the PCM.


Do not disrupt the programming session.
Do not open vehicle doors or use vehicle accessories.
Do not attempt to program vehicles whose battery voltage is lower than 11.5 Volts.
Do not attempt to use the vehicle to power or charge the laptop. If it is necessary to provide additional battery power to the laptop, use an external battery that is not connected to the vehicle.

Rewrite Entire (selected vehicles only)

This is a useful feature for the tuner shop or mail order tuner and doesn't apply much to a single-vehicle tuner. What this can allow you to do is program a VCM that came from another vehicle for your specific vehicle type. You must make sure that the VCM hardware matches. This is a very powerful feature and must be used with caution. If you write a VCM with a file that doesn't belong on it, you could damage the VCM and cause it to be unrecoverable. It is not available for all vehicle types.

VCM Recovery

When rewriting the VCM, critical components of the VCM software must be erased and re-written. If the VCM loses power during the writing of these critical system components, the VCM may become unrecoverable. Do not power down the VCM under any circumstances during a write failure using these advanced options.

"Write VCM" failed and now my car won't start, what do I do?

Don't panic. An error has occurred during the write process. Follow these guidelines:

Make sure the vehicle has sufficient battery voltage for programming.
Make sure your laptop has sufficient power.
Make sure all communications cables are connected firmly.
DO NOT pull your VCM's fuse or disconnect battery power in an attempt to correct the problem.
Restart VCM Editor and open up the same file you wrote to the VCM when the error occurred. It is very important that you use the same file. Try to Write VCM again.
If the problem persists, contact customer support. See Contacting Customer Support.