May 2020

MAY 2020 AFTERMARKET 33 EYEBROW www.aftermarketonline.net memory). It can remember such things as the security link between the anti-theft system and other data, for example injector correction factors used for smooth running control and adaption memory for example the EGR valve. One reason a switched live is used is so that when the ignition is turned on, the module wakes up and is ready to work, and when the ignition is turned off can go to sleep and doesn’t drain the battery. There are other reasons for both which also can vary depending between petrol and diesel and manufacturers. Again, it’s important to have the correction information to hand to know the system operation. Polarity With my information to hand I gained access to the ECU, which on this model is located behind the battery. Testing each power and ground under load proved all to be good, so according to Topix we now needed a new control unit as the incorrect polarity jump start has damaged the control unit. At this stage I was in agreement, and decided to phone my local dealer and price a new unit up. Brand new, this control unit was at the time around £800 plus VAT, then required fitting and programming. I then took a step back and had a think about if anything else could be done. I remembered many years ago reading an article by James Dillon, where he advised always thinking of what tests you would do if the part/repair did not fix the vehicle and doing them beforehand. With this in my head I then thought what else could I do? What if it was just a software issue and a possible update would rewrite over what may just be corrupt data? I myself had never seen it before and did not know the answer but for the sake of updating the software with the Land Rover factory scan tool I decided to give it a go. If it didn’t work then I was happy it needed a new ECU and I had learned something in the process. The module did have an update available so I ran the procedure and then when complete I cranked the engine to see what happened. To my surprise the engine fired into life and all of my fault codes cleared except the 2 x EGR faults which after further testing were both faulty (a common issue on this particular engine). The vehicle was rebuilt and given a road test and all was well confirming the complaint was fixed. The customer was then notified and advised of the EGR issue. Lessons From this job, I learned that if there is possibly another test that can be carried out, do it and see if any more information can be gained. On this vehicle it was looking like a new ECU, so I had nothing to lose. It was just an idea I had, which I decided to do follow through on in the name of learning, due to my curiosity. Will this work every time? I highly doubt it, as in this case only the software was corrupted. If a large amount of current had made its way into the unit, then the small and fragile components would not have stood a chance which is what usually happens if they aren’t protected by a fuse. Luckily for the customer the repair only turned out to be a fraction of the cost of a new control unit and a lesson learned for his friend. www.aftermarketonline.net I learned that if there is possibly another test that can be carried out, do it ” Fig. 2