This error code if for a Toyota walkie pallet. Code E115 is a Main Contactor Fault. Contact tips might be welded together, one way to test this it to visually inspect the contact tips and see if they are stuck together, lightly tap the contactor and see if the tips come loose.
The contactor is not working correctly. Check wiring and voltage associated with contactor. Test resistance with your voltmeter setting on ohms and see if it has an open circuit. Typical readings vary per contactor manufacturer, but resistance may be between 20 and 30 ohms on the coil circuit (the small terminals).
Test resistance across the large terminals on the contactor, the reading should show out of range on the voltmeter. If you have a reading, the tips are stuck closed.