Hi there Eric. Another newbie with a 2002 Golf tdi. Just changed my timing belt about 5k ago. It was really not as complicated as I thought it would be (especially if you already have VAGCOM). At the same time I was also having trouble with a CEL do to a glow plug issue. And yep, turned out to be the glow plug harness. Pretty straight forward to change. I removed the battery/box and air filter box to expose the wiring harness that's housed within the plastic "tunnel". A lot of people unwrap the wiring harness to separate the glow plug harness from the rest of the wires in order to replace it, but I just ran the new GP harness wires separately to simplify future possible harness changes. Haven't had a problem since! Good luck!