In the heat of the fault

Hannah Gordon changes hats this month, and tells us how she solved an interesting fault

Published:  02 November, 2018

At the workshop we cover all kinds of vehicles, old, new, big and small but with all these vehicles we need up to date diagnostic equipment to be able locate faults within the electrical system.
    
In the workshop this summer was a 2009 Volkswagen Golf that had an intermittent issue which meant the car would go into limp mode, the cruise control was disabled and the climate control wouldn’t work. Understandably in the weather we were having the lack of air conditioning was a major concern to the customer. No one wants to be without air conditioning in 30Cº.
    
I plugged in the trusty diagnostics reader and came up with four faults. These included turbo boost sensor, manifold pressure, throttle pedal position sensor and ‘fuel system
too rich’.
    
In my experience cars can throw up all kinds of trouble codes even when there is no issue with that part. I wouldn’t say some manufacturers are more troublesome than others but if a light does appear on the dash it’s best to get it checked out as soon as possible.

Issues
I cleared the fault codes and told the customer to see how it drove and if the issues resolved themselves. The customer had the car for just an hour before they called and said that the problem had reoccurred, as much as this is a pain for the customer I always clear the faults and see if it happens again rather than changing unnecessary sensors. I got the Golf back into the workshop and once again plugged the computer in, which brought up one code. This was the throttle position sensor. A quick call to VW and a discussion with their parts people showed that this particular issue can lead to the cruise and climate control not working.
    
Next day delivery on the part means the car came back in the following day. One bolt, two plastic clips and an electrical connection later and the pedal was off. Gone are the days of the throttle cable. The throttle response is now done by a sensor on the pedal which works out how far the pedal is being pushed and tells the engine how to respond. It is clever stuff,  when it works.
    
A pedal replacement on the Golf only takes five minutes and another clear of the fault code before taking the car for a road test. On the test drive cruise and climate control were checked as well as making sure no dash lights had appeared.
    
Modern mechanics have become very computerised. Dash lights appear whether it is indicating an issue with the airbag systems, ABS or engine and diagnostic computers are so important to narrow down what the issue could be. I dislike the reliance that some workshops put on just trusting what appears on the screen of the diagnostics. It is still imperative that mechanics test sensors and look into live data to make sure that unnecessary components are not replaced and the costs put onto the customer, who will have to pay.


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  • Part two The good and THE GREAT  

    In part one, we looked at the start of the ‘diagnostic process.’ The first steps were customer questioning, confirming the fault and knowing the system and its function. These help the technician to build the ‘big picture’ necessary to repair the vehicle correctly.
    In this article we will look at the next four steps.

    Step 4: Gather evidence
    It is easy to overlook this step as many technicians think of it as the overall ‘diagnosis.’ However, once the technician understands the system, gathering evidence will provide key information. This step is normally best carried out with the use of test equipment that does not mean the dismantling of systems and components.

    Many technicians have their own favourite tools and equipment but this list can include (but not limited to)
    the following:
    Scan tool – It is always best practice to record the fault codes present, erase the codes, and then recheck. This means codes which reappear are still current. Remember that a fault code will only indicate a fault with a circuit or its function. It is not always the component listed in the fault code that is at fault

    Oscilloscope – An oscilloscope can be used for a multitude of testing/initial measuring without being intrusive. Some oscilloscope equipment suppliers are looking at systems within high voltages hybrid/electric vehicle technology. The waveforms produced by the test equipment can be used when analysing the evidence and may indicate that a fault exists within a system. An understanding of the system being tested will be necessary to understand the information. This may even include performing sums so all those missed maths lessons at school may come back to haunt you. It may take time to become confident analysing the waveforms, so be patient

    Temperature measuring equipment – This can include the use of thermal imaging cameras. Most systems that produce energy/work will also produce some heat. The temperatures produced vary from system to system. Examples include everything from engine misfires to electrical components, as well as air conditioning system components and mechanical components such as brake and hub assemblies. The possibilities are endless and results can be thought provoking.

    Emission equipment – By measuring the end result, an exhaust gas analyser can show you if the engine is functioning correctly. The incorrect emissions emitted from the exhaust help indicate a system fault or a mechanical fault with the engine

    Technical service bulletins – Many vehicle manufacturers produce technical service bulletins (TSBs) that are generated by a central point (usually a technical department) from the information that is gathered from their network of dealers. Some of these may be available to the independent sector either through the VM or through a third party – It’s always worth checking if these exist. They may indicate a common fault that has been reported similar to that the technician is facing. Some test equipment suppliers may provide TSBs as part of a diagnostic tool package

    Software updates – Many vehicle systems are controlled by a ECU. Most vehicle manufacturers are constantly updating system software to overcome various faults/  customer concerns. Simply by updating the software can fix the vehicles problem without any other intervention of repairing a possible fault. This is where having a link to a vehicle manufacturer is vital in repairing the vehicle

    Hints & tips – Most technicians will have a link or access to a vehicle repair forum where they can ask various questions on vehicle faults and may get some indication of which system components are likely to cause a vehicle fault

    Functional checks – Vehicle systems are interlinked and typically share information using a vehicle network. The fault may cause another system to function incorrectly, so it is vitally important that the technician carries out a functional check to see if the reported fault has an effect on another system. By carrying out this check the technician again is building the big picture

    Actuator checks – Most systems today are capable of performing actuator tests. The technician can perform various checks to components to check its operation and if the system ECU can control the component, often reducing the time to the diagnosis, by performing this task the technician can identify whether it is the control signal, wiring or component or it is sensor wiring. This function can be used in conjunction with serial data to see how the system reacts as the component functions

    Serial (live) data – The technician can typically review a vehicle system serial data through a scan tool. Having live data readings to refer to can help you review the data captured. Using actuator checks and viewing the serial data can also help the technician to identify a system fault

    Remember to record all the evidence gathered so it can be analysed during the next step in the diagnosis. We can’t remember everything. If the technician needs to contact a technical helpline they will ask for the actual readings obtained recoding the data gathered will help.

    Step 5: Analyse the evidence
    Analysing evidence gathered during the previous steps can take time. The technician needs to build the big picture from all the evidence gathered during the first few steps. You need to analyse the information gathered, and decide on what information is right and wrong.

    This step may rely on experience as well as knowledge on the product. You should take your time – don’t be hurried. Time spent in the thinking stages of the diagnosis can save time later. Putting pressure on the technician can lead to errors being made. It may be necessary to ask the opinion of other technicians. If the evidence is documented it may be easier to analyse or share between others.

    Step 6: Plan the test routine
    After analysing the evidence gathered it’s now time to start to ‘plan’ the best way to approach to the task or tasks in hand.

    The technician should plan their test routine, decide on what test equipment should they use, what results are they expecting, if the result is good or bad  and which component should they test next.

    Document the plan – this enables you to review decisions made at this stage in the next step. The technician may not always get it right as there may be various routes to test systems/components. The test routine may have to be revisited depending on the results gathered during testing. Documenting the test routine will provide a map.  Also, don’t forget to list the stages, as this is something that could be incorporated into an invoicing structure later.

    The technician should indicate on the routine what readings they expect when they carry out the system testing. This can be generated by their own knowledge/skill or the expected readings may come from vehicle information which they have already sourced. If the information is not known at the time the test routine is planned, then the test routine may highlight what information is required and what test equipment is needed. You shouldn’t be afraid to revisit the plan at any time and ask further questions on which direction the tests should take. If the plan is well documented and the technician becomes stuck at any point, they can pause the process and revisit later. Also the information can then be shared with various helplines that support workshop networks.

    Step 7: System testing
    The technician then follows their pre-determined plan, if it is documented they can record the results of the test(s) as they follow the routine.

    Many technicians tend to go a little off-piste when they get frustrated. Having the routine documented can keep the technician on track and focused on the result. If the routine is followed and the fault cannot be found the technician may have to go back to the analysing the evidence or planning the test routine. The technician shouldn’t be scared of going back a few steps, as I said previously analysing the evidence takes practice and can be time consuming, not to be rushed.
        
    Summing up
    Remember to follow the process. It is easy to be led off track by various distractions but don’t try to short circuit the process. Some steps may take longer than first thought to accomplish than others. Some distractions may be outside of your control, and it may be necessary to educate others. Practice, practice, practice. Refine the process to fit in with your business and its practices, the business could align its estimating/cost modelling to the process, being able to charge effectively and keeping the customer informed at each stage of the process.

    Coming up...
    In the next article I will be looking at the next four steps which are; Step 8: Conclusion (the root cause), Step 9: Rectify the fault and Step 10: Recheck the system(s). The last article in this series will indicate the final three steps and how to fit them all together in order to become a great technician and perhaps succeed in Top Technician or Top Garage in 2018.



  • IMI launches new international EV training solution   

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    With full-electric car sales in the EU set to reach 200,000 this year, the IMI has connected with Germany’s training academy, Lucas Nülle, to make continual learning convenient and interactive for individuals of all abilities.

    Steve Nash, Chief Executive at the IMI, said: “Making sure that an employer and its employees are ready for the increased number of ultra-low emission vehicles is paramount to future-proofing a business. Being able to service and maintain these vehicles safely should be the key focus, especially when the industry is experiencing the biggest growth in automotive technology that we’ve ever seen.

    “Advances in new technology are creating hundreds of thousands of new jobs across the world, and individuals working in the industry should be adopting this new training to make themselves leaders in their area of expertise. It’s an exciting time for the motor industry and the IMI is committed to making sure we’re ready to embrace the changes that are set to transform the sector.”

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  • Pagid bolsters brake range 

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