Cut to the chase
Damien Coleman from Snap-on discusses how preparation can lead to easier diagnostics
Published: 28 August, 2018
Many modern systems, such as common rail diesel injection, can appear to be so complex that they seem to operate by magic. Over time, such systems are only going to become more and more complex, so understanding them means you can gain a head start on their repair.
You can be presented with a seemingly endless amount of data relating to fuel pressure feedback, fuel pressure control, cam/crank synchronisation, measured mass airflow, injector flow correction feedback, and many other areas.
However, if you prepare yourself with a fundamental understanding of the system and all data available pertaining to the fault, a systematic approach to the fault-finding procedure can be carried out.
Data overload
Figure 1 shows the live data returned from a common rail diesel injection vehicle with an EDC16 engine management system.
There is an enormous amount of data available from these data parameters, which can allow you to ascertain the nature of the fault. The actual operation of the fuel system can be compared to the desired system operation and using the data, a decision can be made on the condition of the system and where a fault (if any) may be.
An oscilloscope is another important tool when investigating a fault with such a complex system. Figure 2 shows an oscilloscope waveform from an Audi with the 2.0L common rail engine. The yellow trace is the fuel rail pressure sensor voltage (feedback) and the green trace is the current flow through the inlet metering valve (command). The waveform was captured during a wide open throttle (WOT) condition.
This image alone tells us that the fuel inlet metering valve is a normally open valve. The engine control module (ECM) decreases the duty cycle when the required fuel pressure is increased. This allows less current to flow through the solenoid and the valve is allowed to open, which increases the fuel pressure measured at the fuel rail.
Full analysis
When the fuel pressure demand decreases, the duty cycle control from the ECM increases. This allows more current to flow through the solenoid which results in a reduction of the fuel pressure. Duty cycle is often referred to as pulse width modulation (PWM) control.
The duty cycle control on the ground side of the fuel inlet metering valve can be analysed using an oscilloscope, as seen in Figure 3. The waveform below displays the fuel rail pressure feedback voltage (yellow trace) and the fuel inlet metering valve duty cycle control from the ECM (green trace).
The oscilloscope is connected to the control wire for the fuel inlet metering valve. The technician must be mindful that this is the ground control circuit. System voltage on this wire indicates open circuit voltage. The diagram in Figure 4 shows the best method of connecting this set-up.
By careful analysis using serial (scan-tool) and parallel (oscilloscope) diagnostics you will now be in a position to identify the area of concern accurately and in a timely manner. Knowledge, together with the right equipment and experience therefore benefits technicians by leading to a reduced diagnostic time and an easier fault finding method, rendering these complex systems much less so.
TT Archives: Top Technician issue ten 2016 | www.toptechnician.co.uk
- A reality check
This year’s summer was good, but as usual, was over too quickly – so back to work and a reality check!
However, during my summer travels some of today’s necessities of life were conspicuous by their absence. I hired a car, only to discover that the USB connection I needed to use to charge my phone and link to my favourite music playlists didn’t work. The local radio station’s dubious choices in music didn’t help relive the tedium, but when I got to the hotel my woes were compounded when I discovered that they wanted to charge a ridiculous amount to use their wi-fi – I mean seriously, who in their right mind can justify charging hotel guests for basic wi-fi – unless the hotel is run by Ryanair (who seem to want to charge everyone for everything), which it wasn’t.
So, with no wi-fi in the hotel room, I had some time on my hands, so I started thinking about the connections we expect in today’s connected world and in turn what connections are needed to run today’s workshop. This got me thinking about the problems it would face if these connections were either expensive, were restricted, didn’t work as they should or didn’t exist at all.
Form over function
Back in the 1990s I remember well being handed a new portable diagnostic tool which could connect to the internet via the mobile phone networks. Subsequently, it was able to conduct remote and bi-directional diagnostics on a vehicle anywhere in the world, when the vehicle was also connected to the internet – effectively ‘PC anywhere’ technology. However, I also clearly remember complaining to the development engineer within a couple of minutes because the functionality was too slow. He was visibly shocked and was clearly offended by my negative feedback on what was his pride and joy. Then I realised what had made me comment negatively – it was not the impressive technology, but the speed of use and the corresponding ability to run the diagnostics I wanted to conduct. In IT terms, this is referred to as system ‘functionality’ and ‘non-functionality’. Simply, the ‘non-‘functionality’ is the design of the system and the ‘functionality’ is what it can deliver. It might be easier to remember this in layman’s terms as being ‘Form over function’.
When applied to the workshop, this directly applies to a wide range of electronic connections that are needed to support your day-to-day business, and if these connections do not work as needed, how this can quickly and detrimentally impact your business activities.
Don’t miss the ‘bus’
The ubiquitous Universal Serial Bus (USB) connection is a good example. A ‘bus’ within a PC are wires that transfer data between components inside the computer, or between the computer and its peripheral devices. We have all come to use this connection for a wide variety of tasks, from using it as an auxiliary power source for many different gadgets, to a vital communications port for various functions such as printers and other data transfer requirements. However, if it does not work correctly, physically or electronically, then simple tasks suddenly become major issues.
This wired technology has moved on and most of us are now connected by wi-fi in the office environment, but increasingly also in the workshop to connect diagnostic tools to the internet. Data transfer speeds depend on the technology used and the latest generation (soon to be 802.11ax) is super-fast, which becomes more important as software updating of vehicles involves the transfer of massive data files. Generally, wi-fi connections work well, but when they suddenly stop working, it is more difficult to diagnose as it is not a physical connection than can be more easily tested. This may happen after a software update and a recent experience showed me how simple a problem can be, but how difficult it was to discover, when my PC was updated and a simple setting was changed. Over three hours of technical support was needed to discover that it was a simple tick-box setting which needed to be re-enabled. These wi-fi problems move into understanding the IT environment of certificates, configurations, permissions, log-in and passwords between the router and the various connected devices, without even starting to consider the wider communications providers that connects your workshop to the wider world.
Have a cookie
This leads me onto an increasing communications requirement which has become a fundamental part of our day-to-day lives, from both the personal and business aspects – the internet. If there is ever a perfect example of living in a connected world, this is it. However, if you think about the wide-ranging possibilities that the internet supports, do you ever stop to think about the technology behind what is happening to understand the control mechanisms that are needed for it to be safe and secure? If you visit a website, not only are there likely to be cookies tracking your choices and mapping your activities, but there will be certificates being exchanged to ensure secure communication. This may extend to log-in criteria and passwords, or may be implemented by the service provider whose website you are viewing. This becomes particularly important when you are paying for something online.
In simple terms, all this is a form of coded access, but this works not only to ensure the correct access rights, but more importantly, to stop anyone who does not have the valid access rights from interfering or monitoring what you are doing.
Control
What then does all this lead to at the workshop level? In terms of the technology of the equipment, then it is developing to be both more reliable and faster, but the same cannot be said of the beloved OBD connector, which is not only restricted in terms of speed, but will become restricted in terms of access without the correct roles and rights authentication which requires certificates from the vehicle manufacturer. As the manufacturer controls this certificate, then it becomes ‘He who controls the connection, controls the function and ultimately the business’, so the workshop of tomorrow needs to worry most about a connection that they have no control over, but which will control their business.
Time then to sign up with one of the aftermarket associations and join the fight to protect access to the in-vehicle data!
xenconsultancy.com
- Autoglass launches ADAS 'Over The Air'
Autoglass has launched the Over The Air calibration solution which adds to its existing ADAS proposition. The combination makes what the company calls the Total Calibration Solution for ADAS diagnostics, coding and calibration.
- blueprint for technical success
Have you ever wondered why it is that some technicians have an aptitude for complex diagnosis? You know the type of tech I mean. They take the seemingly unfixable, dive headlong into diagnostic battle and emerge triumphant time and time again.
Not only that, but they’ll often do so in a time that makes other techs look on in awe! What’s their secret? And more importantly, can you emulate their success? Well, I’ve got some great news for you. You can, and knowing what to do is easy. All that’s required is that you look to the past. History is a great teacher.
I turned 50 this year, and one of the few benefits of increasing age is the ability to spot patterns, and patterns of actions that when followed culminate in your success. Patterns for success surround us, but sometimes you can be a little too caught up in the urgency of the now to spot them.
I’ll show you the patterns great technicians use to triumph in the world of technical diagnosis, and how you can do the same. It’ll be your blueprint for success.
You’ll like the blueprint. You’ll appreciate its simplicity, recognise the logic, and in all probability nod along as you read, agreeing with the steps that need to be followed.
Here’s the deal though: You’ll need to implement it. Knowing the blueprint is easy, but knowing what to do doesn’t get the job done. It’s all in the implementation, and that starts with you taking small steps to achieve positive changes each day. Don’t forget one of my favourite sayings: “Progress NOT perfection.”
I’m as much a fan of the latest technical gadget as the next man. I also love “cool” test techniques, but I’ve noticed that myopic focus on these can often be to the detriment of the long-term technical success of a technician. I’m not saying that you shouldn’t explore “shiny” elements in our craft, but you’ll find huge benefits in building a solid foundation that can be executed on every diagnosis. What do you need to “do well” then? Just these five steps.
Step one – Systemise to win
There’s always a right and not so right way to attack any given fault. One fundamental element is to have a defined system that all technicians use. Without a rigorous system to follow, your diagnosis could be doomed before you start. Here’s an outline of our diagnostic system that just works;
1 – Thorough questioning of customer, establish change point
2 – Confirm and experience fault with customer
3 – Visual inspection for obvious issues
4 – Retreive fault codes, and gather data on what’s required to raise them
5 – Inspect serial data. Note what looks wrong
6 – Research technical bulletins and any technical information required for accurate testing.
7 – Document what’s wrong and possible causes
8 – Form plan and prioritise relevant tests
9 – Carry out tests and draw conclusions
10 – Bypass test to prove the conclusion where applicable
11 – Repair as required.
12 – Carry out postfix operations i.e. component coding.
13 – Carry out tests to confirm repair
Use our process and you’ll definitely be putting your best foot forward.
Step two – Sound electrical knowledge
Now you know what a great process looks like the next part of your blueprint is your understanding of automotive electrics. How quickly you can decide what to test, what tool to use, and what the answer should be is an essential skill that pays huge dividends once learnt. Key elements include:
1 – Becoming comfortable with relationship between volts, amps and ohms
2 – Using voltage drop to accurately find circuit faults
3 – Series and parallel circuit diagnosis
4 – Interpretation and use of wiring diagrams
5 – Fundamental mechantronics test knowledge
Armed with these, you’ll be able to find wiring faults, diagnose sensor and actuator circuits as well as build entry-level bypass tests to confirm your theories. These are skills you’ll use on the majority of diagnostic repairs. Learn these and you’ll reap the rewards for your entire career.
Step three – Oscilloscopes; One tool to rule them all
A little dramatic I know, but understanding how to use an oscilloscope competently is a game changer. It will bring to life all that has been learned in Step two (auto electrics), and when used skilfully will display this in a way that can confirm or deny faults in vehicle circuits, sensors and actuators.
As an example, take just one quick connection (less than a minute on most petrol cars) to the switched side of a manifold injector and you’ll know;
1 – That power supply to the injector is not open circuit
2 – The ECU has control of the injector and is commanding fuel delivery
3 – Time taken for fuel delivery to commence (injector opening)
4 – Integrity of injector ground circuit
5 – Time takes for fuel delivery to cease (injector closing)
Add some additional test points for injector power supply, current and rail pressure (another couple of minutes) and you’ll confirm the integrity of the positive supply to the injector, the injector winding, and a great test for a quick look to ensure the injector is delivering fuel once open. Like I said - It really is one tool to rule them all!
Step four - Generic systems knowledge
With steps one through three in place you’ll now have the foundation knowledge to explore vehicle systems. This can be a little intimidating as there are so many systems and so much to see, which is why we advise attacking this in bite-size chunks. Your goal here is to become familiar with generic items that broadly apply to a wide cross-section of vehicles. While there’s no substitute for formal training, taking a few minutes on a regular basis to self teach is invaluable. Here’s some things for you to try:
1 – Pick one system to start with. E.g. petrol engine management
2 – Select a book or watch a video for some foundation learning
3 – Focus on one part of a system. E.g. Loads sensors
4 – Inspect serial data for MAF and MAP sensors across various load and speed ranges
5 – Scope MAF and MAP sensors across load and speed ranges
6 – Record your results and repeat on different vehicles on the same components
7 – Repeat points one through six on different components
Do this on a range of vehicles and systems and you’ll become incredibly familiar with what good looks like, as well as raising many questions that we’ll answer when you attend our training.
Step five – Manufacturer information and tooling
There’s one final piece to this part of the puzzle and that’s using the using the best information and serial tools.
While I understand that generic information and tooling has its place, I also have too many real-world examples where my blood pressure would have been dramatically raised were it not for O.E. information and diagnostic tooling. My advice here is straightforward;
1 – Select one manufacturer initially
2 – Become intimately familiar with their information system
3 – Learn to use their wiring diagrams
4 – Explore their technical service bulletins
5 – Use their repair procedures
6 – Substitute a generic serial tool for the O.E. tool for a month
7 – Explore all the serial tool has to offer
We’ve been training technicians like you to use this equipment for many years. It’s had too much of an impact for those that have grasped the nettle for you not to give it a go.
You now know what it takes to begin the road to technical success. All you need to do is start. Taking regular steps, and before you know it you’ll have not only reduced your stress but your time to a first time fix as well.
- Insulate to accumulate
There are already over 620,000 battery electric, plug-in hybrid or conventional hybrid vehicles on UK roads. This will only rise, with manufacturers set to dramatically increase production of these vehicles over the coming decade.
Therefore, it’s surprising many garages still don’t have the skills or tools to safely service them. However, Adam White, Director of Workshop Solutions at Euro Car Parts, says there is plenty of help available that can enable technicians and workshop managers can catch up: “Volvo Cars has just signed a multi-billion-dollar battery deal through to 2025, signalling a strong commitment to electric and hybrid vehicle production. In fact, its battery order is so large, it’s more or less equivalent to the entire global production in 2018. This means by 2025 half of Volvo’s global sales, some 500,000 vehicles, will be fully electric. At the start of this year, Ford announced a $15 billion investment and 40 electrified vehicle models by 2022. BMW Group plans to offer 12 full-electric models by 2025. The list goes on and the point is clear, vehicle manufacturers are investing heavily in hybrid and battery electric vehicle technology and it is time to follow suit.”
Adam continues: “The biggest threat to the independent aftermarket is also its greatest opportunity. The greatest risk during this period of transition is that independent workshops slip behind, and customers have no option but to service their vehicles at main dealers. While we see some switched-on garages and younger technicians getting involved with hybrid and EV training, we have a significant amount of data showing a serious industry-wide deficiency in hybrid and EV knowledge and skills.
“Many garages do not see the required investment in training or equipment as worthwhile, believing there to be very few of these vehicles on the road. White suggests the numbers tell a different story. Industry predictions suggest a short-sighted approach to the hybrid and EV market may be damaging to workshops in the long term.”
While optimistic about the aftermarket’s ability to adapt, Adam cautions workshops to approach the opportunity with the right frame of mind and an awareness of the dangers involved with high-voltage systems: “While the risks of working with hybrid and EV vehicles can be safely mitigated, much like conventional vehicles, safety training is critical. For those wishing to test the waters, technicians can be taught how to make the vehicle safe, without the more intensive training on servicing the actual high voltage system. This means if a workshop has one or two technicians who can isolate the vehicle, the rest of the team can safely work on other systems like steering and suspension or air conditioning.
“Many workshops are turning away hybrid vehicles, even when the problem is unrelated to the high-voltage system. While this approach may be sustainable now, we’re at the turning point. Even if workshops aren’t willing to completely commit, having a few staff qualified to make the vehicle safe opens other servicing opportunities. Those who start working on hybrid and electric vehicles now will be ahead of the curve, gaining customers, experience and a reputation for the work. It could be a make or break difference in the coming decade.”
Training
Commenting on training available, Adam says: “Auto Education Academy, Euro Car Parts’ dedicated training platform, offers several appropriate courses, including GED 13 – an IMI Level 2 Award in Hybrid Electric Vehicle Operation and Maintenance. The course teaches technicians how to maintain and repair hybrid vehicles but not the hybrid or electric powertrain itself. Technicians learn about the dangers of high-voltage systems and the differences between HEV, PHEV, EREV and EV. It also covers the various approaches used by manufactures to power down the high-voltage system and the safety equipment required.
“For those looking to repair and replace hybrid vehicle parts, a more detailed and comprehensive course is required. GED 14 is an IMI Level 3 Award in Hybrid Vehicle System Repair and Replacement, giving technicians the skills and knowledge to effectively service and repair EV and hybrid systems. This course lays the foundation for further advanced training. Both courses can be booked through Auto Education Academy.
“It’s free to join, and repairers can login to their own skills portal to view the content of more than 75 different courses. Users can also assess their strengths and identify weaknesses in nine key areas; petrol engines, diesel engines, engine management and emissions, vehicle electronics, air-conditioning, brakes, powertrain, tyres, steering and suspension, as well as hybrid and electrical cars. Results are automatically added to an interactive skills diagram; which technicians can compare with the national average to gauge where they stand.
“Users can see for themselves the serious hybrid and EV knowledge deficiency that exists within the UK. Anyone can go online and complete the skills overview; it’s a great way to understand your personal strengths and weaknesses. It can be a useful tool for managers looking to assess the core competencies of their staff or potential new hires. The data we have suggests knowledge about hybrid and electric vehicles lags far behind other core areas, a growing concern we hope to change.”
Accessible online or over the phone, it provides fast responses to troubleshooting, repair, diagnostics and technical information queries on any vehicle, from any manufacturer.
Workshop Solutions offers four safety equipment packages for workshops working with electrified vehicles. Workshop Pack, Vehicle Safety Pack, Personnel Safety Pack, Safety Tools Pack. There is also a Hybrid Master Safety Pack (£1,099), which includes all four of the above.
“I can understand the trepidation and hesitation we are seeing across the aftermarket,” concludes Adam. “Repairers are focused on looking after their current clients and building a business around what they know. However, things are changing, and we have a widening gap between vehicle technology and skills within the aftermarket. We need to address this shortfall and capitalise on the opportunity hybrid and electric vehicles present to the independent aftermarket.”
The growth in electric and hybrid vehicles is having an impact on many systems that mechanics are, or at least think they are, familiar with. As the segment grows, techs may find they need to re-learn even more than ever before.
Dr Liz Dixon, Global Technology Director of the Shrieve Group, a supplier of synthetic speciality refrigeration lubricants, comments: “Polyalkylene glycols (PAGs) are the lubricant of choice for hybrid and electric vehicle air con. The hybrid/electric vehicle market is growing rapidly and driving up use of electric air-conditioning compressors, and environmental legislation is leading equipment manufacturers to use more environmentally friendly refrigerants.”
European directive 2006/40/EC fully came into effect in 2017. It stipulates that air conditioning systems in motor vehicles type-approved after 1 January 2011 may not be filled with fluorinated greenhouse gases with a global warming potential (GWP) higher than 150. Compliance with this directive led to the development and adoption of R1234yf, which has a GWP of 1.0. In addition to this, R1234yf has a low ozone depletion potential (ODP). Developed to be a drop-in replacement for R134a refrigerants, R1234yf is now the industry standard for new vehicles and r134a is being phased out.”
It’s not all good news though. “Unfortunately,” says Dr Dixon, “the R1234yf chemical structure that ensures a low GWP can also cause issues with refrigerant stability. To counter this, the right lubricant is vital for long-term operation. So, how do you select this lubricant? Fundamentally it boils down to chemistry.
“R1234yf’s molecular structure causes a high level of chemical reactivity. The lubricant must have the correct stability properties to counteract the refrigerant’s inherent reactivity, in addition to appropriate miscibility properties with this new refrigerant type. In this regard, PAG lubricants have the most preferential properties. Electrical systems require further considerations of the lubricant’s conductive tendencies:
“The reason many PAG-based solutions have exhibited such electrical properties is because of how they are formulated and processed. If these PAGs are processed under more stringent conditions to achieve higher levels of purity, you get less contaminants, and a resultant lubricant that is perfectly safe for use in hybrid and electric compressor systems.”
Two in one
On the engine side, for the increasing number of hybrid vehicles, LIQUI MOLY has produced a new additive. David Kaiser, who heads the R&D department at LIQUI MOLY comments: “Strictly speaking, the Hybrid Additive is itself a hybrid, because it combines two properties. It stabilizes the fuel quality and it cleans the injection system. In hybrid vehicles, the electric motor is the main drive. Meanwhile, the combustion motor works only as an assistant. This engine is mostly only used for short periods. This results in two problems.
"First, the fuel remains in the tank for longer and ages more, compared to vehicles powered exclusively by a diesel or petrol engine. The second problem is deposits in the injection tract because of the irregular short-term use. The Hybrid Additive keeps the petrol quality stable, protects against deposits in the injection system and removes existing deposits. It therefore solves both problems. The LIQUI MOLY Hybrid Additive is only for hybrid vehicles with a petrol engine.”
- Ring: Bulb wall chart
Ring has issued a quick-reference wall chart for 6V and 12V bulbs. The chart features images, ECE references, dimensions, technical drawings and part numbers for over 600 replacement bulbs.
The chart also includes information about Ring’s xenon HID range, which features well-established references as well as the newer D5 bulb that is now being fitted on a growing number of vehicles. Research from Ring suggests that xenon HIDs should be replaced every three years, to prevent a drop in light output and maintain visibility for drivers.
Ring’s Vehicle Lighting Product Manager Matthew Flaherty said: “The chart gives a quick reference guide for a wide range of bulb references. We’ve included some of the newest bulbs now being fitted to vehicles, including up to date HID references and the latest in performance upgrades. Our aim is to help technicians identify the correct replacement and offer potential upgrades, so that they can give their customers the best bulb for their vehicle with up to date information and options.”
To order the chart, call Ring’s UK Customer Service Team on 0113 213 7389 quoting part number CAT1248
