We have owned the vehicle from new, I have no idea if the radio codes is there are any.

I had been wondering about disconnecting the battery, on a 'it's no cost and easy to try, what harm can it do' theory.

I guess the radio would be a problem.

Would pulling the fuse to that circuit be same as disconnecting the battery?

No, the radio would not be a problem. Worst case, you may lose the station presets, but you can easily reprogram them. We got off on a tangent, involving moving a radio from one car to another. Sorry if it confused you.

After Googling for the problem, you can no longer convince me that a bad door switch is not causing this.

Perhaps the override switch is faulty too, but everyone who complains about this problem says the override switch does not affect the permanently turned-on light.

Many people say that once the driver's door is considered open, you'll get the "beep beep beep" indicator while you're driving. Until you hit 20 mph. Then once you slow to below 20 mph, it starts up again.

Sounds like DC's Metrorail, except with the Metro, the train won't budge if it thinks a door is open. Thus, all the "please don't lean on the doors" announcements.

yebbut, the reason I say it's not that -apart from it logically not being that- is it was the first thing we checked because it's the solution that works for everyone else. This time we get to be special. lucky us.

Maybe it's not the switch, maybe the wiring to one of the doors has failed.

What we really need is a wiring diagram...

I'll wire your diagram.....

What we really need is a new car

The door ajar light acts correctly.

If you are listenig to the radio and take out the key, the radio stays on until you open the door, I used this as a test of the mechanical switch that detects whether any door is open or closed and it all checked out OK, if you leave a door open the lights go off eventually anyway.
Something has decided against logic to keep the lights full on no matter what, a simple relay would have been nice, but I'm guessing we're SOL there.
The fuse diagram lists a front electronics module, a rear electronics module and a powertrain module.

... like a stuck relay?

you're like a stuck record, that's what. We didn't actually rule that out if you read back, although it makes logical nonsense because you can override the relay with the switch to the left of the console -and that's still working. So even if it was stuck, we should still be able to override it. If this is a wiring issue, then the guy (yup, has to be male) who designed it should be shot..... but we're still investigating the relay issue

What I love about the cellar is the wealth, variety and depth of expert knowledge there is here. What I hate about the cellar is the need for some of the people in possession of that knowledge to patronize and assume idiot-level intelligence in the questioner. And hypocrites. Didn't you just get snitty with tw for making the same point twice, CM?

We can google. We can try what google suggests. We can use other search engines. We have friends in the car industry, Beest works in the car industry. We're smart enough to do plenty of research on the obvious and even the not-so-frickin-obvious before asking The Cellar. We don't tend to bother the genius that lurks here unless the obvious has failed. It didn't fucking work this time. So we expanded our horizons. Don't post snippets of the first google search you did, it's insulting.

Thanks for the suggestions beyond that -we're still working on them, we'll keep you posted if you care.

Well I took it upon myself to ask a friend who is an electrical engineer. After giving him what little info I could, he repeatedly came back to the same conclusion... either the computer or a relay. Sorry I tried to help. Cannot imagine why I tried to do that for you. It won't happen again.

Monster, it might have been helpful if you'd stated in the first post what you had tried/discovered already. We were starting from zero when you apparently were already on step three or four.

So, which maintenance manual, I see Haynes, which was the gold standard in the UK, and Chiltons, any others, any preference?

I've used Haynes and Chilton. I believe it was Chilton when I repaired the cruise control on one of my cars. The diagrams were excellent.

Ford's manual for that vehicle would be the gold standard. They are available from HelmInc.com.