Power draw on a 98 vw jetta gt

There are two problems which might be occurring besides the obvious battery terminals needing to odd wire brushing to expose pure silver lead at the conact posts and inside the post clamps. My 2002 Jetta actually had a crushed wiring harness - Good stuff but it may have been assembled somewhere other than Germany and someone banged the wiring just enough to short or create resistance in the crushed copper. This was solved by a new wiring harness under the hood which also involved the Diesel glow plugs burning up all the time. Second problem may be badly installed diodes in the Alternator. I heard that some have them installed backwards, but only one of them in the group, so of course that would play havock with your charging system even though it will have enough forward power to run your engine. Also the control plug-in wiring on the Alternator sometimes gets salt on it and corrosion then won't let the system be able to get currant to your Alternator to make any power. This is a cheap problem to fix, just buy a new $8 Alternator plug-in and solder it to your wiring cable with good heat shrink wrap insulating tubes and a hair dryer.