General electrical info on modern vehicles?
Posted: Mon Dec 22, 2003 7:47 am
I'm looking at setting up a dual-battery system for myself and possibly a bunch of other cars, friends of a friend who need to run a lot of accessories with the engine off and don't want to risk draining the starting battery. RVs usually have these setups, and they're very straightforward.On one hand, the vehicle's electrical system is pretty simple. Alternator makes power, accessories consume power, battery smooths over the ripples and stores some for next time. But that's the way it's been for nearly a century. If my @$%^@ door-locks are any hint, there's no longer anything simple about cars.One alarming case sticks out in my mind: A friend's Dodge Shadow had a severe overvoltage condition, measured 28 volts at the lighter socket. Simple enough problem, replace the regulator right? No such luck, the alternator is shunt-wound and the regulator is actually part of the PCM in this car. Luckily he found a junkyard PCM!My general question is this: Is there anything weird that I should be aware of, with regard to starting and charging systems on modern vehicles? Are there any good books that'd bring me up to speed on the elaborate crack the automakers have been smoking in the last 5 years or so? I'm specifically curious about:"retained power" accessories and the relays that control themweird alternator setups like the one described aboveany circuits that might be affected by installation of a second batterykeyless entry, remote start, and other electrical nightmaresgeneral tips on getting wires through the firewallfinding wiring diagrams for any vehicle that might roll my wayand anything else you think I should know!