Here are the steps which you should perform to enable test controller logs.

1. Go to your test controller installation directory (typically it is something like C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE\).

2. Open the controller configuration file (QTController.exe.config) and change the trace level to 4 and enable the trace listener as shown below:

  <system.diagnostics>
    <switches>
      <!-- You must use integral values for "value".
           Use 0 for off, 1 for error, 2 for warn, 3 for info, and 4 for verbose. -->
      <add name="EqtTraceLevel" value="4" />
    </switches>
  </system.diagnostics> 

.....

    <add key="CreateTraceListener" value="yes"/>
  </appSettings>
</configuration>

3. Restart the test controller service.

After this the log file (Vsttcontroller.log) should get generated in the same installation directory.