This page, and the links below, are an effort to map out the logic of how to deal with a car problem.
Update, April 2021: We got some excellent diagnostic help from a "driveway mechanic" who specializes in VW TDIs, and then took that info to an auto shop that specializes in high end European cars but also deals with TDIs…it was expensive but I think we got to the root of the problem. The main thing was the wiring in the driver's door, which they pulled out and rewired. There was also some real flooding going on under the driver's side dashboard, which required cleaning out and resealing under the windshield.
2001 Volkswagen Golf TDI
Diesel engine, manual transmission
When it rains hard, the car won't start. This is after sitting in the driveway for a few days, an ordinary circumstance.
No power goes to the ignition; the electric locks don't work; no LEDs or illumination on the dash; turning the key gives no clicks or other sounds.
Possiblities (I think these are the only two):
I think (a)(2) is the place to focus: How to determine *where* the moisture is accumulating to complete a circuit, and draining the battery?
It's hard to diagnose this with Dr. Google, because although many people report similar problems, they rarely give a complete description. (E.g., "car won't start" could mean the engine cranks but doesn't catch, etc. etc.) Diagnose Golf Rain Problem
Related wiki stuff
I'll try to build a model on the Federated Wiki of how a car's electrical system functions. I'll be deepening my learning about cars and wiki at the same time, so it might be slow going.