TOPDON TopScan Master Bidirectional OBD2 Scan Tool

The TOPDON TopScan Master is the top dongle in the TopScan line, sitting above the original TopScan and the TopScan Pro. It plugs into the 16-pin DLC and pairs over Bluetooth with the TopScan app on iOS or Android, so the phone becomes the screen. Coverage runs to more than 120 vehicle brands, and it carries CAN FD and DoIP protocol support, which is what you need to talk to GM and Chrysler vehicles from 2020 up, BMW F and G chassis, and Land Rover from 2017 up. It also handles FCA SGW gateway access so a locked Chrysler, Dodge, Jeep or Ram will let you in far enough to do real work rather than just read generic codes.

For transmission diagnosis the useful part is full-system access to the TCM. A basic code reader talks only to the engine controller, so a shift complaint comes back as a bare P0700 with nothing behind it. This tool reads and clears the manufacturer-specific transmission codes the ECM is pointing at, and streams live TCM data while the vehicle is moving. That means you can watch commanded gear against actual gear, line pressure duty cycle, TCC slip, input and output shaft speed and transmission fluid temperature on a road test, and decide whether you are chasing a solenoid, a wiring fault, or a genuine clutch or hydraulic failure before the pan comes down.

Bidirectional control is the other half of the job. Active tests let you command a component and watch it respond instead of guessing from a code, so you can cycle shift solenoids, fuel injectors, fuel pumps, cooling fans, headlights, wipers and windows from the phone. On top of that it carries more than 30 service functions, including oil reset, electronic parking brake retract, DPF regeneration, TPMS reset, BMS battery registration, steering angle calibration and cylinder balance test. Built-in repair data covers OBD DTC guides, factory technical service bulletins, DLC location and a warning-light library, and the TopFix AI assistant will build a step-by-step procedure with wiring diagrams and connector pinouts off a stored code.

Know the licensing before you order. The tool ships with one year of free updates and full feature access. After that year, advanced functions run on a monthly, quarterly or yearly renewal, while core full-system code read and clear plus live data stay usable without paying. One more thing worth knowing up front: TOPDON restricts the IMMO and key programming functions to units bought direct from TOPDON, so units bought through any retailer, including this one, will not have IMMO. Everything else listed here works. Menus are available in 45 languages. In the box: TopScan Master dongle and quick start guide. Physical size is 3.1 by 1.5 by 4.7 inches and it powers off the vehicle through the DLC, so there is no battery to charge.