Help with S2a electrics and S3 diesel engine/alternator combination

Thanks, on further inspection of wiring diagrams there is an optional interior light feed, purpose colour (no trace). I think thats what it is so at this stage ill ignore it.

Getting into the wiring and so far I have been successful in it (ie, no smoke!). The dash cluster all works with both lights and ignition. I think I am getting my head around the wiring diagrams too as I have been able to chase wires to components and its all making sense now.

However, I have come across something that is either weird by design or my misunderstanding. In early 2a diagrams, the starter button wiring is the connector between the battery and the starter... to my dismay I finally realised the the starter button and ignition switch are independent. The means you can crank over a series engine without the ignition on. Firstly, I think this is ridiculous and an issue for diesel owners as you can effectively crank over a diesel (in hot weather where glow plugs may not be needed) and drive away!! On a petrol its different as you have the coil feed from the ignition, which is at least somewhat theft proof.

Am I correct in my thinking that the wiring is meant to be like this? I will be looking at changing the wiring to incorporate the ign key as part of the battery feed to both starter solenoid and glow plugs. Yes I know I can buy the later S3 key, but I still prefer to go with the starter button option.

Petrol Landrovers up to the 1967 change to negative earth used a starter switch that was a simple switch in the main battery lead to the starter - i.e. no solenoid. Diesels used a more or less conventional ignition/heater plug/start switch, located below the instrument panel (no ignition switch in the light switch), that directly switched the preheaters and operated the solenoid mounted on the starter.

If you have converted a petrol model to diesel, as you say, you don't want the engine able to be started without the key. The solution is, as you suggest, to use the starter switch to operate the starter solenoid, feeding it (and heater plugs) from the ignition circuit.

The heater plugs must use a relay, as the rotary ignition switch is not designed to carry that much current.

Thanks John, I cant believe I actually rear the wiring diagrams right lol. I will put a relay in for sure (as I will for headlights that have the inbuilt fuse). Also ill be adding fuses to the other wiring that is unfused!

Although looking at this diagram for a S2a Diesel +tive earth, theres not much there either in being able to start it...
Attachment 148604

That wiring diagram, Figure N1-3 in my manual, I have not seen in the flesh - probably Series 1-2 diesel. My very early 2a diesel had the wiring diagram Figure N1-4, with ignition, heater plugs and starter in one switch, and I was not aware of this one. Reflects a more innocent age, I suspect, along with things such as optional door locks.

Its sad to think things have gone the way they are with anti theft devices nowdays. My father told me that when he was in his 20s you could leave the car, garage and house all unlocked and there was never any problems. As you say, back in the day there was no need to consider these issues.

Back around 1950, an uncle of mine traded in his Rover 9 touring car (no lock, no side curtains) on an Austin A70. He had been accustomed when doing the weekly shopping in Newcastle to just put stuff on the back seat, never any issues. First time he went shopping in the Austin, after carefully locking the doors, someone broke in and stole his groceries!

Edit - typos

That would be right!!

Update... tonight i managed to wire in a relay that is triggered by the coil wire (being a petrol wire loom) and then power is fed to the buttons - one for the glow plugs, the other the starter solenoid. Only way i could do this was to separate the two wires that are plugged into the switch (for feed into ignition) and have the buttons only powered via the relay.

Tested both buttons and worked as expected, so im pretty chuffed I managed this without smoking the loom up lol. Now i have the starter and glow plus only work when key ignition is on, so no cranking of motor with it!

I also got a 850cca, 95amp battery that fits the tray, with correctly positioned terminals for $224. Happy!