Wipers work engine off, wipers no work engine on?

Wipers don't work when engine is on but do when key is in full 2003, Landrover, Freelander -
This is my first post as a new owner and I have a feeling won't be my last by the looks of it.
I have two issues so will post them separately.
My wipers were not working so I checked the internet, dug down to the motor and just before I began to drill out the rivets, and after spraying some WD 40 on the rotor shafts decided to test them out ... and they worked just fine ... after turning the key to the all engage setting. The only caveat is that they don't work while the engine is running, which is rather inconvenient. I did dig out the epoxy on the two leads into the motor but am sure I replaced them properly after cleaning the contacts and refilled the hole with silicone. :boink:
Any suggestions??

Is there a live feed going to the motor when the engine is running?

Good question Iceash.
Will ponder that and use multimeter to see if there is power to the motor when the engine is running. If not then might have to rig a wire to the engine on power feed. Thanks for the suggestion. Will revert with my findings. Always on the lookout for rain these days.
haha