I have a beautiful 1994 Majestic that ran great until it sat for about a year as I was out of state and upon return, key turns, lights on dash light up and there is no crank, nothing. The battery is new but just encase, I hooked to a charger for boost and still no reaction. My thought is an electrical/ security kill device that prevents ignition. I read the owner's manual and didn't see any reference to this problem. I realize my mechanical limitations which is why I appeal to the Forum for a miracle!

 

Inertia switch?

 

I guess, a bit of extra information would be helpful. 4 liter L6 or V12. What else does NOT work and what is working.
As a start: Wiggle the gear lever.
Otherwise, please provide info re: line 1 of this post

 

Waldoch, your intuition is spot on. The starter circuit chain of events and devices is long and torturous and there's room for failure in corroded connections, the soldering on circuit boards, several relays, multiple controllers, and then there is Jaguar's paranoid British fear of bad guys under every rock LOGIC programmed into said controllers. Let's assume all the electrical/electronic circuitry in your low mileage garage queen is primo and works perfectly as a starting point. We could reach for the FIVE 3 ring binders that comprise the Factory Service Manual and the year specific massive PDF electrical diagrams, been there, done that, it does not solve the problem. Or grab that 300 page saloon handbook and find Security in the index at the back. Seven pages of discussion pgs 27-33 about all the security features that hint at the logic buried somewhere distributed amongst the "central processing unit" (otherwise known to us Yanks as a Body Control Module BCM and the elusive never mentioned "security ecu", both of which have much to say about what's going on during startup.

First "feature" mentioned: starter motor immobilise (you *******s)

Lots of babbling about "armed" vs "disarmed" that I have no idea how dealers ever explained to affluent buyers who were actually going to drive themselves instead of telling their chauffeur "James, figure it out".

Fast forward to "Additional Features" and find
Battery tampering alarm restart mode
which redirects you to
Emergency Disarm Procedure (active arming only)

That one column of text will keep you busy for a day. I'm not going to quote it since you have the book.
But before you run off, check out the next column that says
Security System Shutdown (What????)
I will note a couple points there, abbreviated
Security left armed for 3 days, intrusion and inclination shut down to save power.
Then there's the 28 day thing about shutting off the keyfob radio reciever which just happens to reside in the security ecu.
And what to do about it.

Spend as much time on that page 32 as necessary until you are thoroughly confused. This whole conversation requires a couple of hours and I'm not going to write a master class today. I will be documenting that evil little security box in the future and separately the entire chain of events of key twist to vroom but I have to box up a ZF rack and pinion right now to get my core charge back.
Cheerio!

 

Second @newyankees post ..try moving/wiggling the gear selector. If the car doesn't think it's in P or N it wont crank. Common issue.