Hi Mr. Russo, Jeff here to assist you with your starter problem. Your electronic remote on the key chain is for a system that is not original equipment. It may have been installed by the dealer where it was first sold, but because there is no published wiring it would be virtually impossible to work on. Even if you had the wiring diagram we don't know where the installing technician made his connections-though this diagram would help us to bypass what it controlled from the module connector(s). If you're really fortunate, the multi-function module [MFM] that was installed will be readily visible under the dash and
it will have the name of it's manufacturer on it. If you're really lucky as well, presuming this was a dealer installed system, they'll still be in business. If the stars are shining brightly over your Jag, they'll be able to get you another remote. From experience though, I wouldn't count on it. Your starter circuit is very simple and there are two locations where the circuit is fairly easy to access. The first image is the system wiring diagram; it shows us what color wires we're going to look for.
The line labeled WY [white with a yellow stripe] represents the wire going from the Ignition Switch to the Starter Relay, and this is usually where the circuit is interrupted by alarm systems/anti theft systems and remote start systems. We'll go after the relay output which goes directly to the starter, a circuit hardly ever cut into. This wire is labeled WR [white/red stripe] and should be visible at the relay, which is located for us in the next image:
This will be on the firewall, and the wires might still be taped up. There will be two that are much larger than the others, the WR will be one of them. To jump the starter you will need a remote starter switch -or- a heavy 10 gauge jumper wire with good alligator clips. A remote starter switch is a hand held momentary button style switch mounted in an easy to hold handle, with a length of paired wires and clips at the ends. One clip goes to the WR wire -make this connection first using either method- the other goes to battery positive at the battery. If you can get the clip on the wire without touching the other terminals that's great-otherwise we'll need that wire removed from the relay. If there's still some insulation around the terminal at the end of the wire that connects to the relay, you can insert a small screwdriver and attach the clip to that; be careful not to spread the connector open or it will have to be squeezed a bit when you reconnect it to the relay. We're jumping about 10 amps to engage the starter solenoid, and the clip on a jumper wire might get hot really quickly when you touch it to the battery terminal-if you use this method I'd suggest taping it up or otherwise protecting yourself from a burn. Once we're connected at the WR wire, either press the button or touch the battery positive terminal; the solenoid should click and the starter motor should spin the engine. This will happen even if the key is out of the ignition switch. If the circuit was interrupted between the relay and the starter then this won't work, so If you get no reaction, move the clip at the relay right down to the starter [or you could go here first, it's a bit deeper in the engine bay where things get incredibly dirty and it involves leaning over which can be strenuous]. The starter has only two wires, one that's huge and our little [in comparison] WR friend. The connection at the starter may be a spade terminal or a screw; clip to the screw or pull the wire off and clip onto the spade. If the key is in the ignition in the RUN position, and the MFM isn't wired to kill anything else, the engine should start; at the very least it will turn over.
Watch out for moving parts.
I hope I've helped with your starter issue. Please let me know if you need further assistance, I'll be waiting for your reply.