SCOTTY!!! My family a 2001 mk4 gti with the 2.8 vr6 engine and a manual transmission. It runs very well mechanically, but the battery drains within an hour! Battery is brand new, all fuses are fine, and we did a parasidic draw test on all the fuses, made sure nothing was running even going as far as unplugging the stereo and it still keeps draining!!! The ONE thing we havent tested is the alternator diode because it is VERY hard to get to, requiring that we take off the serpentine belt and risking that we break the tensioner. Should we go ahead and have a mechanic replace the alternator and the wire that goes to the extra fuse box from the alternator, or is there something I am missing with my testing?
good alternators are expensive. I don't think I would replace it unless I had proof.
Can't you just unplug the other end of the alternator cable?
why would the tensioner break? That doesn't sound safe.
You can load test the alternator and the battery at any auto parts store. If the battery is draining in an hour, it sounds like there is a dead short somewhere. When you connect a test light or multi meter to neg battery terminal and the disconnected neg cable, does the light come on or is there are reading on the meter. Are you sure you checked all the fuses in all the fuse boxes? There are several in the car.
https://fuse-box.info/volkswagen/volkswagen-golf-iv-mk4-1997-2004-fuses-and-relay
To follow up on what Ive seen:
On vr6 gtis the tensioner is EXTREMELY tight which is why I alluded to not wanting to replace the alternator without being certain. I tried to follow the alternator cable to the diode but its too tight of a space... perks of vw ownership lol.
Yes, I checked every single relay, every fuse, and every wire. But I did NOT check the ground wires at the time.
A couple days later, I found on the VW forum to check a ground coming from that alternator cable going to an engine mount... I disconnected it, sanded, and put it back on... left it for a night and the battery didnt drain.
Scotty is right about these being electrical NIGHTMARES as they age, but the ride quality and fun I get from it is worth the headache sometimes. Especially since I bought it for DIRT cheap. DO NOT BUY unless you have too much time on your hands like I do.