The present invention generally relates to the field of testing computing devices. More specifically, the present invention relates to a system and method for testing a universal serial bus ("USB") within a computing device. In an exemplary embodiment, the system includes a test device and a test control module. The test device is connected to a USB port on the computing device. The test control module resides on the computing device and interacts with the test device to test the USB port. Once connected, the test device is used to monitor signals on the USB port exchanged between the test device and the USB port. Examples of signals that are monitored are the voltage levels, frame timing, and USB bus signals and power voltages. The test device then communicates the monitored information to the test control module for analysis. The test control module is further capable of causing a second set of tests to be performed including a full-speed device detect test, a bulk transfer test, an isochronous transfer test, an interrupt transfer test, and a low-speed device detect test. The results of these tests are then communicated to the user.