[goz007]

As for the earth question, i.m.o 100% can cause issues & the same as U describe the hotter the wires get the harder to move the current pushing IR through the roof untill the circuit fails....as for the battery, yeah like I said, I've seen it 2many times the most recent was that SZ 760cc testing as a good battery indicator in the battery also solid green(but really that's just a false sense of security as it's only looking@1cell)but CCA was testing around 640 but battery test matching(expensive well known brand)was saying good battery) also struck another one that sticks in my mind on a Mazda 800cc battery, battery testing good & showing 780cca green indicator green 12.8v@rest car would start & drive perfectly, drive for hours without any issues, park it in the sun(was hot & summer@the time) it wouldn't start, park in the shade & it was ok... checking battery when it had the no start issues battery was still checking good, eventually after many attempts to diagnose (left it@anthor mates workshop as he found the situation quite funny & wouldn't believe me-until it did it to him(it was his sparky who said battery is U/S we laughed at him, he laughed back at us-car was in its no start state-had been driven out of the workshop sat in sun all day & then wouldn't start, sparky said I bet U a carton of carona that I'll put a new battery in & it will start.... well he took home a carton of carona.) although both these car are different to your situation(also both these cars were different to each other as well) the point being that with these modern cars that run a high demand on the power supply from a battery can play havoc with there modules.... batteries do strange things & batteries aren't made like they use to be & aren't really made to last any longer than 3yrs.....i.m.o 3yrs smile & be happy as uve done well