Mk5 Wiring

[HairyFool]

I have the Haynes Transit manual which specifically says it does not include Motorhomes so the question is not about those.

I find some discrepancies about wire colour coding between the actual and the Haynes.

The Engine bay has two batteries and the Motorhome manual has an addendum about Ford changing from 1 Starter + 1 Auxiliary to both starting. Sure enough I find a heavy cable coming from each battery to the starter motor.

The only post 95 diagram in the Haynes with two batteries directly linked then has a 3rd battery. As the book states it does not include the Motorhome models what is this 3rd battery, did it ever exist?

To cross refer is there any alternative wiring diagrams to compare with?