A bidirectional scan tool, also known as a bi-directional scanner, allows two-way communication with a vehicle’s onboard computer systems. Unlike traditional OBD2 scanners that only read diagnostic trouble codes (DTCs) and data, bidirectional scan tools can also send commands to activate specific components and systems. This ability to both read and control vehicle functions makes bidirectional scanners a powerful diagnostic tool for technicians and advanced DIY mechanics.
What is Bidirectional Control and Why is it Important?
Bidirectional control refers to the capability of a scan tool to send information to, and receive information from, a vehicle’s electronic control units (ECUs). This two-way communication enables technicians to perform active tests, also known as actuator tests, functional tests, or system tests. By sending commands to various components, like turning on a fuel pump or activating a relay fan, technicians can pinpoint the root cause of a problem more efficiently. This eliminates guesswork and reduces diagnostic time. Reprogramming certain modules is also a function of bidirectional control.
For instance, if a cooling fan is not functioning correctly, a bidirectional scan tool can command the fan on and off to determine if the issue lies with the fan motor itself, the wiring, or the ECU controlling the fan. This targeted approach saves time and money compared to traditional trial-and-error diagnostic methods.
How Does a Bidirectional Scan Tool Work?
A bidirectional scan tool connects to the vehicle’s OBD2 port and communicates with the various ECUs using standardized protocols. When a technician initiates an active test, the scan tool sends a specific command to the designated component. The component then responds by performing the requested action, confirming its functionality or revealing a malfunction. The scan tool receives and displays the results of the test, providing valuable diagnostic information.
Examples of Bidirectional Scan Tool Applications
Bidirectional scan tools offer a wide range of applications, including:
- Activating Relays and Solenoids: Testing relays for cooling fans, fuel pumps, ABS systems, and more.
- Controlling Actuators: Testing actuators for throttle position, EGR valves, variable valve timing systems, and more.
- Performing System Tests: Running comprehensive tests for specific systems like ABS, transmission, and emissions.
- Module Reprogramming: Updating or modifying software within certain control modules.
Example: Innova 5610 performing a purge valve diagnosis.
Choosing the Right Bidirectional Scan Tool
Not all OBD2 scan tools offer bidirectional capabilities. When choosing a bidirectional scan tool, consider factors such as vehicle coverage, software updates, user interface, and specific features needed for your diagnostic tasks.
Example: Innova bidirectional scan tool performing an active test.
Bidirectional scan tools provide a significant advantage in automotive diagnostics by enabling active testing and precise component control. They are essential tools for professional technicians and serious DIYers who need to accurately diagnose and repair complex vehicle systems.
