Scan Tool Features

To understand what scan tool level is appropriate for you, obtaining a high level understanding of the features they offer can be very helpful.

A scan tool is useful to: (not all scan tools can perform all of the following functionality)

Access OBD-II Diagnostic Trouble Codes (DTCs) and associated freeze frame data.
DTCs along with thier associated freeze frame data are used to determine what issue(s) the ECU has encountered. You can use the OBD-II decoder to learn more about what a DTC means.

There are Generic DTCs, meaning all manufactures must use a described set of DTCs for well-defined issues.

There are also manufacturer specific DTCs, used to indicate errors due to their own unique way of implementing the defined EPA and CARB standard. Since manufactures are constantly upgrading their individual implementations, to work on newer model years and utilize their manufacture data, an upgrade to the scan tool is required yearly.

Access OBD-II Parameter IDs (PIDs), e.g. Throttle Position Angle %.
PIDs represent the current state of sensors, e.g. Vehicle Speed, and internal run-time information, e.g. Short Term Fuel Trim.

There are Generic PIDs, meaning all manufactures must provide a known set of information for diagnosis.

There are also manufacturer specific PIDs, used to monitor manufacture specific functionality used to fulfill the defined EPA and CARB standard. Since manufactures are constantly upgrading their individual implementations, to work on newer model years and utilize their manufacture data, an upgrade to the scan tool is required yearly.

This data can either be presented in a textual like format, e.g. Speed : 0 km/h, or in a graphical representation. Some PIDs are best viewed in a graphing format, e.g. Air/Fuel sensor. Some tests cannot be performed as effectively without graph output. For example, to test an Air/Fuel Sensor functionality, one test involves snapping the throttle and watching how the sensor behaves. The graph below is the successful execution of this test on a Toyota Corolla.

Vehicle Speed and Intake Air Temperature - Textually Loading....
Air/Fuel Sensor - Graphically Loading....


Clear current DTCs
Sometimes fixing an issue will clear the associated DTC(s), but the technician will have to wait for several full cycle drives before the code to clear. Other times, the code must be cleared. So, more often than not, once the issue is resolved, the technician will monitor the appropriate PIDs to ensure the fix resolves the issue, clear the error, and return car to customer.

Bi-Directional Control
Many times the technician needs to verify that a particular component is functioning appropriately. For example, energizing an EVAP Valve Solenoid in conjunction with a handheld vacuum pump allows it to be tested. To accomplish this, bi-directional commands are sent from the scan tool to the ECU that then performs the instructed operation. Clearly, knowledge of the ECU sub-systems are required. For the most part, these tests are done with the Key On and Engine Off (KOEO). But one example of a test executed with Key On Engine Running (KOER), is testing the Idle Air Control Value. Using bi-directional control, the IAC is opened and closed and the tachometer is used to determine that the test is successful.

Bi-directional control is manufacture specific.

Numerous Connectivity and Platforms
Scan Tool Connectivity

This diagram depicts Connectivity and Platform options.

Connectivity

A Scan Tool can connect to an automobile in a variety of ways. All Scan Tools connect to the automobile's computer via DTC female port found usually under the driver-side dash. From there it can connect directly to the scan tool via a cable, or the connector can utilize blue tooth technology to allow the scan tool software to execute on a tablet or mobile phone.

In some high-end scan tools, they leverage an additional RF transmitter that connects directly to the automobile's DTC female port, which extendeds the scan tools range and extended information throughput.

Platform

In regards to platforms, the scan tool software can execute on a:

Clearly the more powerful the platform(CPU, memory, storage, graphics capabilities), the more functionality the scan tool software can implement, display, graphing, logging, ....


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