Straight from our help file
www.hptuners.com/help ( a very good read)
Writing the VCM
There are a few different ways you can write to the VCM. They are:
- Write Calibration Only under the "Flash" menu or by clicking the red colored "Write Calibration Only" icon on the toolbar.
- Write Entire under the "Flash" menu (advanced users only)
- Write VIN/Tunerlock/VATS under the "Flash" menu (advanced users only)
"Write Calibration Only" is the regular, safest and fastest way to rewrite the VCM.
ALWAYS use "Write VCM" when making regular tuning changes.
The "Write Entire" and "Write VIN/Tunerlock/VATS" options are special features to be used by advanced users only and are discussed further below.
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 on for all vehicle types.
Frequent Questions
When should I use "Write VCM" ?
All the time except in the circumstances described in the following sections.
Never use the following methods to recover a VCM that has failed during a normal Write VCM operation.
When should I use "Write Entire" ?
The
only time you should use the Entire VCM Write feature is if you are updating the software on the VCM to a new operating system. For example, using a Corvette VCM with electronic throttle in a Firebird that has cable driven throttle body (same VCM hardware, different Operating System).
If you are recovering from a standard VCM Write failure, using the Rewrite Entire feature will not help ensure the recovery of your VCM. In fact, in a failure scenario from a standard VCM Write you are at more risk for total VCM loss when you try to recover using the Rewrite Entire.
When should I use "Rewrite VIN/Tunerlock/VATS" ?
The only times you would need to use this option is if you have updated the VIN of the VCM (via the editor), are relinking the VATS system or are applying the Tunerlock feature to lock or unlock the VCM. Generally these things only need to be done once (and can be done during a "Write Entire" as well).
Note: It is a good idea to try and limit the advanced writes (Entire and VIN/Tunerlock/VATS) to only once. ie. setup the new operating system with all required VIN, Tunerlock and VATS information and then choose "Write Entire" for the first write only. Then use the normal "Write Calibration Only" option for regular tuning.
Originally Posted by Bill@HPTuners
