Normally a single ground wire is used in vehicles & further the ground is shared via body which is made of mild steel & not a very good conductor hence causes high resistance. In mech. Based vehicles it doesnt effect much but in EFI each and every part of engine is connected via connector so high resistance causes load on battery & alternator. U can see this differance while on a start vehicle, turn on the lights, then ac i.e increase the electrical load gradualy and see the rpm it will fluctuate with load , but now after installing this apparently i've seen control on the rpm which is stable now further i'll experiance & share inshaAllah
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