Sorry, I don't know exactly where it is, or even if it exists. Lacking any other replies, I'm willing to offer some suggestions:
I've a feeling there is mention of power windows in the engine bay fusebox, but I'm guessing you already looked there. Most relays are under the dashboard near the steering column. In case you didn't know, there's another fusebox there too so it's worth checking the fuses in there. The Haynes manual says Fuse 6, but this might well vary between marques. There is an autodown relay in the driver's door, but I doubt this could be the fault you are describing since it would only affect one door. A fault in both doors would suggest a common fault.
I made this image for an entirely unrelated reason (autodown modification for passenger door), you'll notice Item 179 - Honestly I can't remember what this is and I can't find the book! Could be a relay, or maybe ignition switch?
Sorry I couldn't give more precise information.
