Hello! I have a 1967 MK2 that I bought and it hasn't run since 1997. It's a serious bit of a project, but I wanted to see if I could start by getting it running. It had no ignition switch when I got it. So, I got a used switch from an S model . Now I'm looking to wire it up. There are 5 prongs on the s model switch, however I only see three wires behind the dash area. I assume the S model was far more optioned. The wires behind the dash are 2 white wires and 1 brown with white stripes. This somewhat matches the wiring diagram I downloaded from the FAQ links. Except there is the one spare white wire. I have a feeling I bit off a lot more than I should have. LOL. I used the search feature, but I couldn't find anyone with pics or relatable info. Thank you for any help you might have!

1967 MK2 with 3.4liter/automatic

 

You're post in a bit confusing, you say there are three wires total, 2 white and 1 brown with white.
Then you say there is an extra white wire.
So is there 3 wires altogether or 3 white wires and 1 brown with white for a total of 4 wires ?

Do you have 3 or 4 wires.

At any rate you need to get a multi meter and do some continuity tests to the S-Type switch to find which terminals to use.
The ignition switch is no more complicated then a wall switch, just off and on, you just have to determine which terminals make and brake contact and the multi meter will tell you that.

A photo would help, I'll have a look at my car tomorrow and take a picture.

According to the wiring diagram, the brown and white wire is the feed (hot) from the ammeter, and that is connected to the feed from the battery.
When the ignition switch is ON, it connects all three wires together.
The two white wires will be either connected together at the switch or when the switch is on (run position) all three will make contact.

 

On the S Type ignition switch there are only three wires according to my wiring diagram. NW or Brown white which is the live feed from the battery. There are then two W or white wires. The first goes to the starter button and then on to the starter solenoid. The second white wire goes to fuse unit three which feeds all the items you need to run when the ignition/key is switch on such as lights and horn when the engine is not running. The wiring for the Mk2 I would assume is the same as the cars are based on the same workings.
1960s Jaguar wiring was very easy to work out as there are no modern junction multi switch boxes or relays all over the place so I would do as JeffR1 suggested and get a simple continuity tester and check where the wires are going and also check across the terminal of the switch so you can tell when the switch is on and to which terminals the flow will go.
If you have a third white wire this will be another feed to the fuse box which will become live only once the ignition switch/key is turned. A continuity test will determine which fuse it feeds but all the white wires should be dead until the ignition/key is switched on or you will drain your battery should they be constantly live.

 

The two white wires are connected through the switch weather it is off or on.
When ON, the brown and white wire connects to the white wires internally in the switch.

On you five terminal switch, use you continuity test to determine which of the terminals are connected or disconnected in the off/on mode.

 

Really wanted to thank you guys for the help! Finally got the switch wired up successfully!