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New Year – Fresh perspective

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By John Batten | Published:  29 January, 2018

Into 2018, John looks at the steps you need to take to make your workshop more efficient, while obeying the Laws of Diagnostics

January has to be one of my favourite months of the year.  Not only might there be the opportunity to get in a cheeky weekend away skiing, but that first day back at work gives you the opportunity to implement the changes you’ve been planning at the back end of 2017 that’ll drive your businesses to the next level. It’s all VERY exciting!

You’ll no doubt have new marketing campaigns to launch and front-of-house techniques to increase sales, but do you have a plan to increase the efficiency in your workshop? There are many elements to consider when it comes to improving workshop efficiency, but ensuring that the correct technician has the necessary skills to complete that task in a timely manner should be pretty close to the top of the list. After all, one of your largest expenditures will be your wages bill and it’s critically important to the success of your business that you sell all the hours you buy in bulk from your technicians.

Would you throw away £50 notes for fun?
I talk to a lot of automotive businesses and when it comes to a fault finding mission we find that it’s not a case of whether a vehicle gets fixed or not, but a case of how long it takes to get to that fix. Where a diagnosis has meandered it’s also not uncommon for the number of hours charged to be reduced, compounding the pain felt by the business owner. The perseverance displayed by the technician is admirable, but it can have the ability to hit your bottom line in a big way.

Consider a realistic (and very conservative) example where a technician doesn’t have the fundamental skills to diagnose a vehicle in a timely manner. Let’s assume an rate of £55 per hour. If you had one technician with two jobs a week that ‘meandered’ by an hour on each of those jobs the loss in profit for that technician would be close to £6,000 for the year. Increase the hours ‘meandering’ or the number of technicians and the loss in profit can become quite scary. Here’s the cool thing though; accepting that this is happening in your business is the first step required to reclaiming all that lost profit. The second step? Implement change.

‘Take the first step in faith’
Great! You’ve decided that 2018 is the year to change your business. You know that helping the ‘right’ technicians in your business acquire the relevant skills is not only good for them but great for staff retention, as well as helping your bottom line. What to change first though? It can often seem like a daunting task just planning how to move forward but as Martin Luther King Jr said: “Take the first step in faith. You don’t need to see the whole staircase, just take the first step.”

So what’s the first step? That one’s quite straight forward and the subject of a previous article. Process, with the right step by step process (at AutoIQ we use a 15 step process), diagnosis becomes a lot less frustrating. It’s the second step (and a what a crucial one it is) that’s the technical focus of this article.

The very next step...
Right on the heels of a great process is a VERY thorough understanding of all things ‘Auto Electrical.’  Without this, life as a technician can be frustrating as it’s often this foundation knowledge that’s required to understand why serial data acts as it does, as well as how to test EVERYTHING with a wire on it. In addition, if you’d like to use a scope to reduce your diagnostic time (and why wouldn’t you?) then having this electrical knowledge is the difference between understanding the waveform and making a decision based on that information, or looking longingly at the wiggly line and hoping the answer will jump out at you. Here’s the good news. Anyone can learn this. Yes, really. Anyone.

The Laws of Diagnosis
OK, so you buy into my “I gotta learn this electrickery business,”  tell me what I need to know! This is where we need to tread carefully, very carefully. Whilst I could wax lyrical about the laws within physics that underpin diagnostic theory most technicians switch off at the mention of Ohm’s law let alone Kirchoff’s, Maxwell’s and the many other laws that silently weave their way through our diagnostic lives. Does that make them unimportant? No! They just need to be brought to life and given a little on-vehicle relevance.

Let’s take a look at an example and how a little electrical understanding when it comes to parallel circuits can point you in the right direction for network diagnosis. Fig 1 shows the equation to work out the total circuit resistance for a parallel circuit with six resistors. I could use the rest of this article to explain this equation, or I could cut to the chase with a quick tip on the “need to know” knowledge that’ll give you a quick resolution to the problem that follows. Which would you prefer? I thought so,
quick tip it is. Here’s what you need
to remember: “The equivalent resistance (total resistance) of a parallel circuit will always be lower than the lowest resistor. “
  
Have you got that? Good. Don’t forget it as you’ll need that later.

The example we’ll use is a VW Golf in a non-start condition and no serial communication to any ECUs on the Powertrain network. There are numerous fault codes, all for communication issues for the ECUs on the Powertrain CAN network. Fig 2 shows the CAN network with six ECUs connected in parallel to the bus. ECU 1 incorporates a 66Ω terminating resistor, ECUs 2,3,4,5 and 6 have internal resistances of 2600Ω’s (approximately) each. Powers and grounds to the control units have been tested with no issues found. CAN High and CAN Low have been scoped (Fig 2) and when compared to a good waveform it doesn’t take much working out to see that something is VERY wrong.

The key to efficient diagnosis is to act only on what you know to be fact. “Yes this system is operating correctly” is great as we can continue our process to the next test. ‘Yes’ we’ve found a fault is also great. ‘Maybe’s’ are dangerous ground and can lead a technician to an incorrect diagnosis, something we definitely want to steer clear of.

What can we tell from our bad waveform and are there any additional tests required? It’s plain to see that there’s an issue and a follow up test for bus resistance could prove useful here. The bus resistance was tested to reveal the 474.5Ω and therein lays the answer to our communications fault. You did remember the quick tip didn’t you?  “The equivalent resistance of a parallel circuit will always be lower than the lowest resistor.” Well… If the bus resistance is higher than the lowest resistor (66Ω in ECU 1) then it stands to reason that ECU 1 is not connected to the network (open circuit or very high resistance) or the terminating resistor has a resistance much higher than it’s 66Ω specification – a check at ECU 1 will reveal the fault. Ours was an open circuit in the CAN harness at ECU 1.

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Keeping it simple and moving forward
All being well you’ll see the importance of the laws in physics that our diagnostic success is based upon. More importantly you’ll understand that it’s not all about equations or maths but about breaking this into ‘bite sized tips’ that reveal diagnostic answers when practised.

What will you be doing in 2018? The same as you’ve always done? Or improve the skills of your technicians, increase efficiency and reclaim thousands of pounds in lost profit?

Would you like to learn more about John’s system for diagnosis? If so, then call Auto iQ on: 01604 328 500

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