[Cartmaster]

I apologise for multiple posts here but the timing means i lose the chance to Edit a previous post.

I was nearly right about the crank circuit. There is definitely a neutral switch involved, probably on the gearbox with a light green wire. so if that is not engaged the starter may not crank. You should be able to test this by grounding the green wire and it may crank. There appears to be no other safety switch in the circuit. If you follow the wire back, it goes directly to the -Ve side of the coil on the start relay, but tee's off to the ECU. Not sure about that, but assume the ECU either reads a ground or supply's a ground. the other side of the relay coil goes to the ignition switch on a black wire with Red Trace ? (cant see the diag clearly enough) the starter motor activation wire goes to the starter relay switch and the other side of the relay switch goes to a fuse and back to battery +. So with this info you can trace the circuit easily. I suspect a fault on the ground side of the activation circuit not pulling in the start relay. This may be why somehow putting those bunched wires on the -ve battery post is somehow supplying ground to the relay ?????

First place i would look would be the neutral switch and work back to the relay. I am assuming the +ve side of the circuit is good as it cranks when you place those wires on the wrong battery terminal -Ve.

Just my thoughts at the moment. Hope it helps.


[EDIT]
Just had a brain flash. Now i can see the diagram a bit clearer, Your wires that are bunched together that you moved from -ve to +ve has a blue/red wire attached. It looks like this may feed the fan relay, so that may be your issue with the fan? it needs to be on the +ve side of the battery for the fan to operate. Try cutting this wire and re terminating it as a single wire back on batt +ve. Dont forget the engine still needs to be hot to activate the relay, or bridge the sensor connector.

If this proves good, then we can concentrate on the crank circuit possibly missing it's ground connection at the relay. It also looks like the white wire in that bunch feeds other accessory connections, so maybe something is wrong here. maybe a short, or something giving you a phantom ground connection. Now i can see the diagram more clearly, i think maybe your issue is just a fault in the crank circuit ground somewhere.

You could try refitting the blue/red to see if that sorts out the fan, then do the same with the white wire to see what happens with the crank circuit and go from there. I honestly cannot see that the whit wire is causing an issue as it just goes to a fuse and then out to accessory connections, but who knows what a previous owner has done in the past.

At the end of the day, if you solve the fan issue, you can probably overide part of the crank circuit if this is for your personal use and just wire straight from the ignition switch to the starter.

Not being able to be there personally it is difficult to really diagnose with just that image of the cables and a diagram. To be honest wire colours on the diagram are really difficult to see.