Abstract: The present invention relates to a method for controlling a tool string having a downhole self-propelling wireline tool having wheels rotated by means of hydraulics and connected to projectable arm assemblies projected by hydraulics, comprising running a downhole self-propelling wireline tool into a wellbore, the downhole self-propelling wireline tool being connected to a second end of a wireline, and a first end of the wireline being connected to a power supply, the downhole self-propelling wireline tool having a tool body and a plurality of wheels rotated by means of hydraulics, and each wheel being connected to a projectable arm assembly projectable from the tool body by means of hydraulic fluid from a first hydraulic pump, the downhole self-propelling wireline tool having an electric motor rotating at an operational rotational speed for driving the first pump; supplying electric power to the downhole self-propelling wireline tool to operate the downhole self-propelling wireline tool at a first speed to ur