Do a search on disarming, I know there is info on it.

But just for grins redo that starter ground. A solid ground will do nothing other than help, it certainly cannot hurt it. If the starter does not have a really good ground, it will intermittently give you the NOTHING phemomena. Redoing my ground was all it took to cure mine.

 

The Discovery has several different grounds, you need to make sure the motor, frame and body all have a common ground. Savannah had some good background with ground problems.

 

re: unlocking with the key doesn't disarm it.

An important clue. The door lock has a mechanical side and an electrical switch. Your switch function must be bad, so you can't disarm and then crank truck (per the norm for the alarm). You can open the kick panel under dash, locate connector C2101, find the blue and green wire wire on pin three, and aply a momentary ground to simulate operating the lock switch. You can also remove door panel and get to same wire at door lock. Door panel is not as easy to remove. Truck will not crank with alarm armed. See attached.

 

New info: I dug into the dash to find the spider box, and I don't think I have one... unless its behind the duct work or something, but from what I understand it should be visible once the radio, hvac controls, and plastic surround have been removed. Is that right?

Also, savannah, as far as disarming... I tried that when I was having problems before with no luck, but I'll try it again.

I still don't have an answer to my other question: is there some sort of 'alarm ecu'? It seems like all the problems I've had are related but not the same... just leads me to believe that something like that could be the issue.

 

If you push the plunger down on the driver's door, do all the other doors lock?

Did you check what Savannah said regarding the door?

 

The central locking function WAS working but stopped when this last problem cropped up.

As for the door, I know for a fact that the alarm switch in the cylinder is NOT working but the switch that runs the central locking is... or was, anyway.

 

I suggest you print the Electrical Troubleshooting Manual and read thru it to get familar with the various systems. Get a decent multi-meter. I bought a nice little GreenLee at Home Depot for thirty bucks.

Take your time and verify the door switch wiring is working properly even if you have to pull the panel off the door. There are a lot of things that tie the door locks into the alarm system. For example: if you have the alarm on and unlock any door other than the driver's door with the key, the alarm will go off.

If you have the door open and push down the lock, they will all cycle down then back up. Like Savannah said, the unlock is electrical, so verify yours is good.