"Diagnostic tools can be a great time-saver by allowing technicians to pinpoint elctronic and electrical faults more quickly"
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GOLDEN RULES
Five top diagnostic tips from Daniel. Barker, technical manager, Texa UK
• Speak to the driver about the fault and, ideally, perform a road test in order to confirm the problem.
Thirty minutes spent at this stage can save you hours of misdiagnosis and needless problems.
• Identify the vehicle and the system, including checking its engine codes and ECUs.
Manufacturers may use more than one ECU in a range of trucks. If you guess wrong, you could get incorrect information.
• Always use the diagnostic socket to power the diagnostic unit.
If you use the tool on auxiliary power, there is no communication with the ECU, and, in any case, if there is no power to the diagnostic tool, that may explain the vehicle fault.
• Fault codes are there to help a technician in their diagnosis. They don't necessarily mean the part it is indicating is faulty and has to be replaced. Its worth remembering that fault codes do change over the life of a model range as newer ECUs are installed to replace older ones.
Print out a list of the fault codes this will help you understand which codes are relevant to the current problem and which are just old ones.
• If the ECU has no record of a fault, that indicates the fault is probably mechanical and there is no failure of the electronic control system.
Older ECUs simply won't register mechanical problems. but newer ones are more intelligent and might record a mechanical problem as a symptomatic fault rather than as an actual one.