DIAGNOSTIC TOOLS

I have seen the Uber x MD+ diagnostic tool advertised (pictured). Can you con rm how this system actually works to diagnose powertrain-related issues of vehicles? JENS KERNECK Klerksdorp

Naturally, we can evaluate products only once we have physically tested them. From the picture, it is clear that this is one of the generic OBD scan tools that connects to a vehicle’s onboard diagnostic port. It usually communicates to another device (like a smartphone or tablet) via Bluetooth.

The OBDII was introduced in the US during the 1990s and the equivalent EOBD standard in Europe only in 2001. The standard de nes the communication protocol used by a vehicle’s electronic control module (especially the ECU) for diagnostic information. When the ECU detects a problem with a sensor, actuator or system, it stores a diagnostic trouble code (DTC) in its memory and, depending on the fault, may illuminate a warning light (malfunction-indicator lamp).

Many DTC are legislated (especially the emission-related faults) and they must therefore be visible to a generic scan tool. There are other faults that are manufacturerspeci c and are not visible to such a tool, but only to the manufacturer’s service systems. A modern vehicle can easily have more than 500 fault paths (with DTC) in the powertrain system alone.

The scan tools should also provide realtime data such as engine speed, vehicle speed and manifold pressure, to name a few. These channels are again regulated by the OBD standard and may be useful for fault diagnosis or even the recording of vehicle data for eet purposes.

A modern vehicle has many ECUS, all connected on a single network called the CAN bus. The OBD connector connects to the CAN bus and serves as a port to connect to many modules, including transmission, instrument cluster and even the ABS unit in some cases.