F4 HDC AMT mulpile signals

It sounds like the gearbox control cable is out of synchronisation, and needs adjustment.
The cable turns a crank on the bottom of the box, which then links a rotating rod through the box to the switch module on the top.
The gear selector lever has sensors, which light the lights, and also tell the TCM where the lever is. The TCM also gets signals from the box switch module, and compares the two. If the cable adjustment isn't correct, then the TCM gets conflicting data, so it assumes a fault, and sends the F4 signal to the dash LCD. There is a setting procedure in the workshop manual, which needs to be followed to set the relative positions, or it'll never work correctly.

Have you tried moving the inhibitor switch by loosening the 2 10mm head bolts? There isn't much adjustment but it might be enough to stop the 2 lights illuminating at the same time. Also check the white insert in the XYZ (inhibitor switch) is lined up as in the pic. As said mark bits before you loosen anything. Should have said this is in P & there is a keyway in the shaft coming out of the g/box that the white plastic bit in the XYZ switch slides onto, be careful with the switch as the white plastic bit (in the middle of the switch) will be brittle after all this time & you don't want to snap the lug off it which locates it on it's shaft,all the best.

Thankya both very much lads
I've ordered a Haynes manual so I'll look into the syncronisation of the gearbox control cable when that arrives !
In the mean time I'll scribe around this inhibitor switch and have a play with the adjustment.
Thank you both tho !