Unless it has already been engineered you will need to get it done as the motor was not standard with that vehicle. The sparky must be useless if he doesn't know how to check and find a battery drain if one exists. You have to connect your multimeter and see how much current is being drawn from the battery, 0.03A is the maximum you will want to see when the battery is connected. Battery drain can be an accessory, light or relay that is still on when it shouldn't be.. Basically you check for live fuses and pull them one by one till the battery drain disappears, Then you know what was causing it..