The claimant dropped his tractor-trailer off at the insured location to be loaded with grain. He left the tractor-trailer parked and unoccupied there overnight but took the keys with him. He was going to return the next day when the truck was loaded to take the grain to the mill. While it was parked on the insured premises and the claimant was not present on the premises or with the vehicle, the insured hit it with the combine and caused damage to the tractor portion.
I believe the insured accepted a bailment of the claimant's tractor-trailer when the claimant parked it on the insured premise and left it overnight. When the claimant left the tractor-trailer parked there overnight, he left it in the insured's care custody and control and this is excluded on GL2.
Exclusionary language on GL2
EXCLUSIONS
"We" do not pay for a loss if one or more of the following excluded events apply to the loss, regardless of other causes or events that contribute to or aggravate the loss, whether such causes or events act to produce the loss before, at the same time as, or after the excluded event.
2. Additional Exclusions That Apply Only to Coverage L -- Coverage L does not apply to:
d. damage to property that is rented to, occupied by, used by, or in the care of an "insured", except for "property damage" caused by fire, smoke, or explosion.
Pennsylvania Subscriber
We do not see any coverage under the policy for this loss of a motorized vehicle that is not used to service the premises. The exclusion you pointed out would deny coverage for property of others that is in the care, custody or control of the insured. However, the vehicle owner took the keys with them so the insured could not have moved the vehicle to prevent it from loss. The insured did not have care, custody or control simply because the vehicle was parked on the premises since they had no key with which to control the vehicle. The premises liability coverage does not extend to motorized vehicles not being used to service the premises. This business was not a parking lot and not subject to covering non-owned vehicles left on their premises. The coverage for damage to property of others does not cover motorized vehicles not being used to service the premises.
This being said, the insured could have liability for the damage under the policy that covers the combine. If you would like us to review that coverage, we will be happy to do so.

