November 2019

Sensor simulators can often be used but not for all situations. Lastly, but most importantly, always remember that a lack of understanding often results in smoke Let’s keep it simple. What’s required to simulate this particular MAF sensor? Nothing more than a varying analogue voltage on the signal wire between 0.6 volts and 4.5 volts dependent on the air mass drawn in. How is that created? Like this; see fig. 1. A straightforward voltage dividing circuit can be created from a few pounds worth of electrical components, or a sensor simulator can be used. As time was of the essence Steve borrowed our sensor simulator. Most simulators are capable of creating a range of analogue and digital signals for the common vehicle sensors so it was just a case of Steve selecting the right option and dialing in the required voltage. Steve dialed it in and was overjoyed to see the behaviour of the data. Lambda was now in the correct range, and emissions values were spot on. Armed with this information Steve had the confidence to fit an OE sensor and fix the vehicle. From stress to success What lessons can be gleaned for Steve’s pain? An OE sensor fixed his vehicle; Having a test plan leads to correct diagnosis; Bypass testing prior to component replacement confirms diagnosis; Bypass testing gives you confidence to buy expensive parts; Bypass testing reduces your stress. There’s a lot to like about a bypass test. It’s worth bearing in mind though that a lack of knowledge here can result in blown components, fried ECUs and the production of smoke. It’s worth gaining the knowledge on when and how this can be used in your diagnostic process. Used correctly though it’ll drive down the time it takes to get to a first time fix and reduce your stress. NOVEMBER 2019 AFTERMARKET 25 EYEBROW www.aftermarketonline.net If you’d like to learn how to improve your diagnosis skills then call John on 01604 328500. Auto iQ have a complete technician development programme designed to help your technicians be the best they can be. _____________ To join AutoiQ’s online forum go to: autoiq.co.uk/ garageowners