A concrete deck slab from a major Canadian bridge has undergone an extensive condition assessment using non-destructive testing (NDT). The bridge suffered from extensive use of de-icing salts during the winter seasons, combined with frequent freeze–thaw cycles, and hot and humid summers. Although numerous and extensive maintenance and rehabilitative measures were completed on various components of the bridge, the severe deterioration continuously reduced the structure’s service life. This paper presents the results of the corrosion potential and state of the temperature reinforcement embedded in a post-tensioned concrete deck slab that had suffered deterioration from chloride-induced corrosion. NDT techniques including half-cell potential mapping and the connectionless electrical pulse response analysis were implemented on the embedded steel reinforcement. Concrete electrical resistivity measurements were also obtained from the concrete surrounding the steel components. Although no signs of corrosion-induced concrete cracking were identified at locations around both layers of steel reinforcement, both layers still exhibited high corrosion rates. However, corrosion was more severe for the top reinforcement possibly due to the penetration of high concentrations of chlorides from the bridge deck. In addition, concrete surrounding the bottom reinforcement was characterized by low surface resistivity values, indicating moderate to low chloride ion penetrability resistance, while concrete surrounding the top reinforcement had high surface resistivity values, indicating very low chloride ion penetrability properties.