Reading and Clearing DTCs

When you begin tuning a new vehicle, ALWAYS check the vehicle for diagnostic trouble codes (DTCs) and resolve as many as you can before you do anything else. 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's current tune will clear all DTCs, resulting in the loss of the troubleshooting information they contain. DO NOT read the tune until you have checked for DTCs here and resolved or made note of any issues reported.

Follow these steps:

1.

Physically connect your laptop to the vehicle. See Connecting to a Vehicle.

2.

If VCM Editor is open, close it now.

3.

Open VCM Scanner.

4.

Turn the vehicle ignition to a position other than OFF. (The engine can be running or stopped. But, the vehicle must supply power to the OBD-II port.)

5.

Click the icon in the toolbar to open a data connection to the vehicle.

6.

Click . The Diagnostics & Information window appears.

7.

Click Read DTCs. VCM Scanner will query the vehicle for diagnostic information. When finished, any DTCs detected will appear in the top half of the window.

8.

Some vehicles report additional "freeze frame" data for individual DTCs. If this data is available for your vehicle, it can be viewed on the Freeze Frame tab.

9.

Use the provided information to resolve as many issues as possible before tuning the vehicle.

10.

If desired, you can click Clear DTCs to tell the vehicle that the issue has been repaired.

NOTE: Clearing DTCs resets the emissions monitors. This will cause the vehicle to fail emissions testing until it completes the tests performed by the emissions monitors. These tests typically take several drive cycles to complete.

NOTE: If an issue has not been successfully repaired, a cleared DTC will be reported again.