Diagnostics for a positive prognosis

On-board diagnostic (OBD) scan tools have become a staple in all modern workshops. GARETH GREATHEAD finds out what they do and how their use contributes to a healthy return on investment.

Pieter van Zyl, owner of Roodepoort Auto Diagnostic, explains that diagnostic tools are essential in order to understand, maintain and repair modern vehicles. In addition, many service and repair procedures can be performed only with a diagnostic device.

“Modern vehicles have complex modules and sensors which all work on the controller area network (CAN Bus) protocol, whereby binary code is sent between the many sensors and the engine control unit (ECU). These communicate with each other just as a central nervous system does in our bodies,” explains Van Zyl.

Van Zyl explains that OBD scanners can help an organisation save money by preventing breakdowns and keeping as much work as possible in house. “Diagnostic tools can retrieve stored data in the form of a fault code, as well as live data about how efficiently an engine is performing.”

For example, when it comes to servicing, many diesel engines have diesel particle filters that require active regeneration services, which can be undertaken in house with the right tools. On the other hand, if there is a fault with something like the oxygen or lambda sensors, this will be flagged.

If these issues are not identified, the engine will continue to run rich, wasting fuel and polluting the environment. “Diagnostic tools therefore supply information that can reveal potential problems and prevent expensive repairs or breakdowns down the line,” says Van Zyl.

Other parameters that are monitored include ignition timing, fuel-injector performance, working pressure of high- and low-pressure fuel pumps, engine revolutions, air and coolant temperature, crankshaft position and
speed.

Before diagnostic tools and software became available, only basic mechanical tests could be performed. There was also a lot of guesswork involved in diagnosing a problem and making an accurate diagnosis was often a case of trial and error.

Van Zyl says: “Today, every system can be monitored, recorded and compared. The computer will also tag each data point to see where there is an abnormality so that the technician can look for problems in a specific system.”

What to consider

Diagnostic software and devices must be compatible with the vehicle mix in order to work optimally. Before investing thousands of rand in diagnostic equipment, it is therefore important to undertake some research, consult others in the industry with similar needs to the operation, and exercise due diligence by shopping around.

It is important to remember that training is an essential part of getting the maximum value from the investment. Van Zyl adds: “When purchasing these products it is usually a case of ‘you get what you pay for’. Systems range from those used by original equipment manufacturers to cheap Chinese imports with limited functionality.”

Other suggested steps to take before buying a diagnostic tool include comparing pricing for the technology’s annual software updates, comparing warranties, analysing potential replacement costs and, finally, taking note of the extent of the technical support that will be provided.

In conclusion, diagnostic tools have the capacity to save transporters money through the early identification and rectification of events, as and when they occur. They also simplify the repair process and provide peace of mind for managers, drivers and technicians.