Aftermarket September 2022

BY Kevin Toms R ecently we had a 2009 Ford Transit Connect 1.8 TD come through the doors with 140,000 miles on the clock. The customer explained that if he drove the vehicle above 2,500RPM, the dash display all fell to zero and the engine would cut out. Then, within a second, it all came back online and would drive again, until the next time he hit 2,500RPM. The van already had a new alternator fitted in an attempt to resolve the issue, but this had been unsuccessful. Armed with that information, a test plan was drawn up as follows: 1. Road test and verification of the fault 2. Global scan 3. Result-driven approach 4. Look up fault code 5. Gain access to relevant information, know faults and fixes, wiring diagram. 6. Equipment required; multi meter, scope etc. What type of testing voltage and continuity using a scope to monitor signals while system is operational. 7. Study results from testing and plan a fix 8. Apply the repair and retest 9. Prove repair successful including road test 10. Write up job card and return keys and job card to the office. 32 AFTERMARKET SEPTEMBER 2022 TECHNICAL www.aftermarketonline.net OVERVOLTAGE ADVERSITY Kevin was not shocked when a Transit came in with some interesting electrical issues, so he got to work Step 1: Road test. This lets us experience and validate the customer’s concern. I didn't need to go far as a quick acceleration up the hill had it doing its thing. The dash suddenly all fell to zero and the engine cut out. Then, just as quickly the dash came back to life the engine picked up and away the van went, until the next acceleration. Upon returning to the garage, a test plan was put together. Step 2: Attach the scanner and do a global scan. This is always my preferred method, as the way systems interact means the same fault code can appear in many other systems. If we only concentrate on a single control unit, such as the ECU or dash, without considering the vehicle as a whole, we can miss vital pieces of evidence that could identify the reason for the failure. While the scanner was running through the systems check, I opened the bonnet and carried out a visual inspection. There was nothing obvious to report there, so I just verified that the new alternator was installed as described. How many of you are saying dash fault right now? We have all seen them. Next, I checked the scanner fault report, which was where I found the golden nugget; Overvoltage. Step 3: Results-driven approach . Having read the scan report, I highlighted the recurring fault code with the same description in each ECU it appeared. In fact, overvoltage