Update #2
Update #2
Haffiman nailed it. Incorrect wiring. Negative from battery (B-) connected to +ive starter input terminal. Yep... ouch.
The funny thing is, the so-called OMC Power-On Self-Test worked just fine. Each time the ignition was switched on, the tach would cycle through the lights and beep OK. Still scratching my head about this. I guess as Haffiman said, the circuit was being completed through the brushes and the Self-Test assumed there wasn't a complete moron at the other end.
Well, I did say in the very first post that I know zero about starters : )
Essentially, every time the starter switch was engaged, the battery was shorting itself! Which would explain why the cables were getting hot. This is also why the electrics seem to have been spared; no current was actually flowing through the sensitive bits.
I can report the relay is working fine and continuity is OK... phew.
However the battery is quite flat now so I need to hook it up to the charger before I have enough amps to crank. Will send a final update later.
Thanks to everyone for their help, esp. Haffiman!
I'd also like to apologise to everyone who suggested hot-wiring the starter directly. I'm sorry, I didn't realise that terminals E &F were independent inputs - I thought they were a common ground. The insulation on E is not very apparent else I would have caught on earlier. Sorry!
