Service vehicle soon light

If the service engine soon light is on and there are no codes then the most likely cause of this is either a code that your reader is not picking up or a loss of communication with the ECM.

Here is a guide that will help with the most common causes of the ECM:

https://www.2carpros.com/articles/check-engine-light-top-ten-reasons

When you hook your scan tool up, are you able to actually communicate and view the PCM/ECM information?

If you are then I suspect the scan tool is just not cable of recognizing the type of codes that are there. Most generic scan tools will only pick up powertrain issues which are P codes. If you have communication or more electrical codes like U, C, or B codes then you scan tool may not be capable of reading them.

Here is a review of a scanner that is capable of this and not too pricy:

https://www.youtube.com/watch?v=XY-1CsAzrFA

Please run through this info and let us know what you find and we can go from there. Thanks