November 2020

NOVEMBER 2020 AFTERMARKET 25 chain; Fig.2 cover housing; Fig.3 Parts assembly. The vehicle is still enjoying an elevated position awaiting my report for the insurance company, which requested to know what caused the problem. I have penned many reports and have prevailed in all my expert witness cases, and smell another one here, or it could be the beef noodles and bean sprouts? Second topic Next, we have an AUDI A6 2.7 CRD presented to us as a trade-in into a Vauxhall dealership. The problem is that it is cranking with intermittent no-start. Initial checks were carried out showing a DTC, ground short to power on the in-tank fuel pump relay. I am often amused with this description, as if it was taken literally there would be smoke and probably fire as the loom fuses together rather quickly. Please refer to Fig.4 relay location r/h. Time to call Diagnostic David. Why the definition? Well, we have three Davids at ADS. Diagnostic David bridged the relay 30-87 terminals in order to run the pump and the vehicle started every time. He then conducted wiring integrity tests between the PCM and pump relay focusing on terminals 86-85. No problems here, power was present from supply right back to the ground control circuit at the PCM. The obvious conclusion an internal PCM ground switch error? This is where you MUST take a pause? Why? Because you have discovered the symptoms NOT the cause. David then exposed the edge connector between the loom and PCM. Please refer to Fig.5; Oil on PCM socket. David elected to expose the board in the PCM and visually check for component damage. Please refer to Fig.6; control chip blister. Visual evidence shows blister damage to a controller chip suggesting excessive load. Having discovered oil on the edge connector we now need to prove the cause. So, we are looking for capillary invasion through the loom from a component with access to oil. The usual and obvious components oil switches showed no oil invasion on the sockets. In fact, the search proved difficult due to limited access. However, David eventually discovered the path of capillary invasion back to #5-injector socket. This engine variant (see Fig.7) uses piezo injectors, and to my knowledge I have never heard of or experienced this type of problem. The electrical connector is external from any lubricant, so the problem must be internal from within the portion that is exposed to lubricant. Fig.5 pcm edge connector showing oil ingress Fig.6 a6 pcm showing blister damage to board component

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