What scanner do GM dealerships use?
GM dealerships primarily rely on two tool families: the Tech 2 handheld diagnostic scanner for older GM models, and the MDI/MDI-2 networked system running GM’s Global Diagnostic System (GDS2) for newer vehicles, accessed through GM’s TIS2Web service. The Tech 2 handles diagnostics on legacy cars, while the MDI-GDS2 setup enables extensive diagnostics and programming on current models.
Two generations of GM diagnostic scanners
A quick look at the two main tool families you’ll encounter in GM service bays and what each one does.
Tech 2 handheld scanner
The Tech 2 is a portable, GM-specific diagnostic tool used on a wide range of older GM vehicles. It connects via K-line or CAN networks and supports diagnostic coding, basic adaptations, and some configuration tasks for legacy ECUs. While increasingly supplemented by newer systems, many shops keep a Tech 2 on hand for vehicles built before the modern MDI/GDS2 era.
- Portable, GM-specific diagnostic tool designed for legacy vehicles
- Reads and clears codes, views live data, and performs some basic programming/adaptations
- Works with older GM modules that aren’t compatible with newer web-based systems
- Usually paired with a service subscription or license for newer software access
Although dated, the Tech 2 remains a staple for owners of older GM models and for certain special procedures where newer tooling isn’t required.
MDI and GDS2 (modern GM diagnostics)
The MDI (Multiple Diagnostic Interface) and its successor, MDI-2, connect GM vehicles to the dealer network and run GM’s Global Diagnostic System software (GDS2). This setup supports advanced diagnostics, module programming, and software updates on current GM vehicles, with access tied to GM’s TIS2Web portal and the SPS programming environment.
- MDI/MDI-2 hardware that interfaces between the vehicle CAN networks and GM service software
- Runs GDS2 for diagnostics, programming, and calibration tasks
- Connects to GM’s TIS2Web for software updates, vehicle information, and download access
- Supports comprehensive reprogramming through the Service Programming System (SPS) when needed
In practice, technicians rely on the MDI-GDS2 stack for most modern GM work, including software updates and module programming, while the Tech 2 stays in service for legacy models or particular procedures.
How modern GM diagnostics are performed
In dealership service bays, the diagnostic work typically follows a defined workflow that blends hardware with GM’s software ecosystems. The steps below outline a common sequence used today.
- Connect the MDI to the vehicle via the OBD-II port and to the shop network.
- Open GM GDS2 (via the TIS2Web session) and select the appropriate vehicle application to retrieve fault codes and vehicle data.
- Review live data and fault codes to identify root causes, often using guided test sequences and data streaming.
- If needed, use the Service Programming System (SPS) to reflash or calibrate control modules with the latest software.
- Document findings and ensure any software updates are applied, closing the session in TIS2Web/GDS2.
Modern diagnostics emphasize software-based repair paths, with the MDI-GDS2 stack handling the majority of routine diagnostics and programming. The Tech 2 remains a valuable tool for legacy models and specialized procedures.
Practical implications for owners and technicians
Access to the full GM diagnostic toolkit is typically restricted to authorized dealers and service centers. For customers, the takeaway is that GM’s service workflow blends legacy and modern tools to cover the entire vehicle fleet—from aging generations to the newest ECUs—through a combination of on-vehicle interfaces, web-based service portals, and dealer-only programming environments.
Summary
GM’s diagnostic toolkit centers on two pillars: the Tech 2 for legacy GM vehicles and the MDI/MDI-2 with GDS2 for current models, supported by TIS2Web and SPS for programming. This dual-tool approach reflects GM’s vehicle evolution, ensuring both older platforms and modern ECUs can be serviced and updated across GM’s dealer network.
What is the best code reader for GM?
The best scan tool for GM vehicles depends on your needs: for professional use, the Autel MaxiSys or Launch X431 are top-tier, multi-brand options, while the official GM MDI 2 is ideal for full dealer-level diagnostics and programming. For enthusiasts or DIYers, the Innova 5610 is a solid choice for bidirectional control and special functions, and the GM Tech 2 is excellent for older vehicles (pre-2013).
For professional use
- Autel MaxiSys / MaxiCheck MX808: A high-end, professional-grade tool with comprehensive diagnostics and support for multiple brands.
- Launch X431 HD Series: Offers professional diagnostics, including topology mapping, parameter changes, and advanced functions, and is a popular choice among mechanics.
- GM MDI 2: This is the official factory tool for modern GM vehicles, essential for dealership-level diagnostics and programming, including online software updates.
- ThinkCar ThinkScan 689 BT: A professional-level tool with a large screen, bidirectional control, and a wide range of maintenance and diagnostic functions.
For enthusiasts and DIYers
- Innova 5610: A solid option for enthusiasts, providing bidirectional control, special reset functions, and free updates, though it lacks VIN reprogramming and high-level key programming.
- GM Tech 2: The standard diagnostic tool for older GM vehicles (pre-2013) and is still a go-to for mechanics working on those models.
- King Bolen Solo Scan: A budget-friendly Bluetooth dongle that turns your phone into a scan tool, offering bidirectional control and special functions for a low price.
- X-Tool D7: Offers comprehensive bidirectional control and over 36 special functions, but check for specific GM online programming limitations.
Factors to consider
- Vehicle age: Older vehicles may require a different tool, like the GM Tech 2, while newer models benefit from the MDI 2.
- Programming needs: Some tools can perform complex tasks like ECU coding, while others are limited to reading and clearing codes.
- Budget: Scan tools range from under $100$ 100$100 to several thousand dollars, so choose one that fits your budget and needs.
What is the GM scan tool called?
MULTIPLE DIAGNOSTIC INTERFACE 2 (MDI2)
Equip your facility with MDI2 to help properly diagnose GM vehicles. MDI2 is a GM Global Diagnostic Interface tool for both current and future GM vehicles that operates with Techline Connect to communicate with a GM vehicle.
What scanner do dealerships use?
Dealerslink OBD gives dealers critical diagnostic information on all used vehicles to include with their trade evaluations. It prevents you from acquiring someone else's problem vehicle by ensuring you see major fault codes and estimates in real time.”
Is VCDS better than OBD2?
For those looking to do those looking to do some simple coding, OBDeleven should definitely be enough. For investigation into specific, rarer problems and installing new hardware, VCDS can prove to be more powerful.
