How to Read, License, and Flash an ECM

Before you begin, ensure that the vehicle is as free of mechanical problems as possible. If there is a mechanical issue with the vehicle, it may affect performance and any performance data you want to monitor could be impacted. This makes it very difficult to tune the vehicle effectively.

IMPORTANT: Reading a vehicle will clear any DTCs (Diagnostic Trouble Codes) from the vehicle's computer, resulting in a loss of the troubleshooting information they contain. ALWAYS check the vehicle for DTCs before you do anything else. See Reading and Clearing DTCs for more information.

Reading the Vehicle

When you read a vehicle, you are transferring calibration information from the control module(s) in your vehicle to VCM Editor. The read process will automatically detect the presence of relevant VCMs in the vehicle and read them all in sequence. The various status messages and the progress bar give information about the current state of the read.

CAUTION: Ensure that the vehicle battery is charged before proceeding (keeping the battery attached to a charger during the procedure is recommended). Although it should not be possible to harm any of the vehicle's control modules during the read process, vehicle controllers can be left in an odd state if a power loss occurs.

To read the VCM, follow these steps:

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

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

NOTE: For vehicles with multiple VCMs (e.g. LS2 A4 vehicles), there is a 15-second pause between reading each VCM.

NOTE: If this is the initial read of the stock VCM, we strongly recommend that you save (and backup) the file before any modifications are made. You may wish to restore your vehicle to the stock tune at a later date.

Writing a Tune Back to the Vehicle

Before you begin, ensure that:

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

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

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

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

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.

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.

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

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