Diagnostic tools and equipment

This chapter covers the types of tools and equipment and other aids that are available to assist technicians to perform accurate and efficient diagnosis and repair of automotive systems. It is not intended to be a catalogue, because there is a large number of companies that make and supply equipment. Addresses of several of these companies are given in the Appendix. Where a particular make of tool has been selected as a case study it is because the makers have supplied the information that enables me to provide the type of description that is suitable for this book, and not because I am expressing a preference for any particular make of tool.

4.1 Diagnostic tools that connect to the ECM

As stated in Chapter 3, the control computer ECM has considerable self-diagnostic power and the DTCs that may be stored in its memory are a valuable source of diagnostic information. The fact that the ECM processor is constantly monitoring inputs and outputs, means that the data that it uses can also be used by any other computer that is using the same protocols (language). This is a facility that microprocessor-based diagnostic tools possess and it enables them to be used to read system behaviour while the system is in operation and also to capture and save data for detailed analysis. In order for this to happen the ECM must be equipped with a suitable serial diagnostic interface that will permit two-way communication between the test equipment and the ECM (Fig. 2.5 shows the general principle of a serial data connector).

As pointed out in Chapter 3, there is movement towards widespread adoption of the USA OBD II and California Air Resources Board (CARB) standard, but this is not universal and the established standard of ISO 9141 is still to be found in UK and European systems. The ISO 9141 standard permits a scan tool to be connected to the diagnostic plug and with the aid of suitable software, usually on a smart card, enables a technician to access fault codes and other data. The Lucas Laser 2000 machine, as shown in Fig. 4.1, is an example of diagnostic equipment that can be used for a range of diagnostic work.

Fig. 4.1 Laser 2000 uses the on-board diagnostic facilities incorporated in the ECU's controlling vehicle systems. The sophistication of these facilities varies considerably across vehicle manufacturers

Fig. 4.1 Laser 2000 uses the on-board diagnostic facilities incorporated in the ECU's controlling vehicle systems. The sophistication of these facilities varies considerably across vehicle manufacturers

Various types of work can be performed with the aid of this machine as follows.

• Reading out fault codes and explanatory text.

• Monitoring (reading) live data as the system is in operation, and displaying the data as bar charts. Several different variables and parameters may be selected and displayed simultaneously for comparison and to aid analysis.

• Data storage. Up to four sets of data can be stored together with time and date of storage.

• Snap shot mode. When in use, during a road test to locate intermittent faults, the machine can be triggered so that data for a period of time before the fault occurred and a period of time after is recorded. This data can then be reviewed on screen so that the traces can be examined for any abnormalities. This aspect of use is covered in Chapter 7.

• Actuator operation. Microprocessor-based machines, such as Lucas Laser 2000, can be used to activate injectors and other devices so that they can be checked independently.

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