[jiggstar]

I see them driving around on the field but every time I want to steal one they are always locked, why?

[miromiro]

Could this help you?

QUOTE (GTAWiki: Harvester Locations)

The Combine Harvester makes its first appearance in the mission "Body Harvest" when Carl Johnson is asked to steal one by The Truth while it is operating at a farm. Upon completion, Combine Harvesters will appear all over San Andreas. Due to its use as a farming equipment, the Combine Harvester is exclusively found in farmland, specifically Blueberry Acres, The Farm and Flint Range. At day, the harvesters will be seen operated by a driver and moving along a predetermined route in the fields; at night, the harvesters are parked in the fields. Almost all encountered Combine Harvesters, especially those at night, are locked, making the vehicle very difficult to steal. In order to obtain one, one may shoot a Combine Harvester's driver at the head, killing them and resulting in the driver falling out and leaving the vehicle's door open for the player to steal. Two can be found at Helena Wankstein's Farm in Flint Range, although theyre difficult to obtain because theyre constantly moving around a crop.

Simply steal one while it's driving on the field.

[AH64Hunter]

Snipe the driver in the morning then when he falls out jack it.