So, I got my ignition switch wired up (thank you forum members). Now I wanted to try and get the starter to move, so that I can try and work towards Starting the car. Well, the battery cables were clearly not oem. And it appeared that it was wired up with negative ground (smaller terminal on the frame cable, larger cable terminal to the starter solenoid). This would tell me that at some point, someone changed the polarity of the car, as it was normally designed with positive ground

Any ideas on what I can check to
determine which way I should wire this up and get it closer to trying to start the vehicle?

1967 mk2. Auto, 3.5l.

Thank you for any insight you have.

 

The car will work either way with the exception of the radio, if the radio is connected wrong it will destroy it.
If the car has been changed to negative ground, and from your description, it has been, then most likely the radio has been changed as well.

If it's been changed to negative ground, then leave it, in my book it makes better sense, especially when it comes to the ignition.
The spark in the plugs works better going from the center electrode to ground (hot part of the plug, to the colder ground electrode), and not the other way around.

Hook up the battery and turn the lights on (do not start the car).
Look at the ammeter, it should move into the negative side if things are correct.

If you're worried about the radio, pull it out and look for a round slider switch on the side some where.
On some of the radios, the polarity can be changed, if it's in the negative position, then someone has already changed it.
Some original positive ground radios can't be changed.

 

Or just see which battery terminal has a cable to the body and or which cable goes to the starter sol.

 

Difficult if the battery had been removed before the vehicle was purchased as is the case with a lot of old barn, garage and project finds. You could check to see which way the coil is earthed if the coil is still wired up. Coil will have a Pos and Neg terminals marked with a + or -. Chase the wires back using a continuity tester to determine which is earth. If the earth is connected to the + then you are still on Pos earth or vise versa if connected to -.

 

Yes, perhaps I wasn't clear in the initial post. Battery was missing from the car when I got it so I'm just trying to piece everything together. Thank you for the insight, I'll start chasing the leads off the coil tonight and see what I have.

 

Also the clocks are positive earth and they will be fried if not converted, or isolated from earth, there is a diode internally which will burn out and kill the clock (if the clock was still working before that is)

 

Watch ammeter it'll tell you.

 

This was very helpful in confirming the polarity. I unfortunately didn't have + OR - on my coil. I had the letters CB and SW. After a quick Google search, it appears CB = +, SW = -. So in the case of a negative earth wired car, CB is coming from the positive lead wire, SW goes to the distributor/earth(ground). Just wanted to clarify my experience in case some one else has the same question. Now onto why the wire between my starter button and the starter solenoid doesn't seem to marry the two?

 

Glad that helped. That is what we are here for.
Going back to the starter button I again reiterate that the wiring on these 1960s Jaguars is very simple and I am not an electrical expert but manage my way around them. There are no relays or multifunction switch boxes like you find on modern cars.
I would start by checking the starter button is actually working by running a continuity across the terminals when the button is pushed.
There will be a single White/Red wire running from the back of the starter button to the starter solenoid on the bulkhead. Check the continuity of this White/Red wire from the button to the solenoid.
If this is all OK it is possibly your solenoid that is defective. Check that you have power running from the starter button to the solenoid when the ignition is on and the starter button is pushed.
If the car turns over when you push the button on the starter solenoid but is still not turning over when the starter button on the dash is pushed you need a new solenoid. They cost about £25 from SNG Barrett.

 

Ive already checked the wire at the push button. It strangely doesn't match the color wiring diagram I have or your reference of white /red stripe. It's white/ blue stripe instead and appears 100% factory. The push button has tested good continuity wise. I'm almost certain the starter solenoid has failed completely and has an internal short to ground as the solenoid makes continuity on both posts without being activated and with the body of car! Yikes. I'm going to do some more digging this weekend and figure out my starter circuit wiring/solenoid this weekend. One step closer! Thanks again for the insight and confining the wiring.

 

For the archives, "CB" stands for contact breaker, ie the points in the distributor and "SW" stands for switch - the ignition switch.