For an improved understanding of the preparation of axial and radial III-V nanowire (NW) structures a suitable electrical NW analysis with high spatial resolution is necessary. We thoroughly investigated the electrical properties of freestanding GaAs-NWs with axial pn-junction applying a 4-point-prober. This UHV-based multi-tip scanning tunneling microscope (MT-STM) is in vacuo combined with a state-of-the-art sample preparation. 2- and 4-point I-V characteristics of the diode are recorded nondestructively, enabling the calculation of the local ideality factor. 4-point-probe measurements at different NW positions results in an axial resistance profile, allowing the determination of the doping concentration of p- and n-doped parts. Investigation of oxide-free NWs enables the determination of very low doping concentrations which would not be accessible for oxidized samples. At the pnjunction a ~500 nm narrow region of low conductance was detected, indicating a compensation effect of dopants during growth. By recording electron beam induced current (EBIC) images, the position of the charge separating contact was confirmed.