Wang's equitable total coloring conjecture

For a graph $G$, let $\Delta(G)$ denote its maximum degree, and let $\chi\,”_e(G)$ denote its equitable total chromatic number, namely the least number of colors in an equitable total coloring of $G$. Wang's equitable total coloring conjecture. For every graph $G$,

$$\chi\,”_e(G)\leq \Delta(G)+2.$$

The source attributes this bound to Weifan Wang (2002) and gives no resolution in the supplied text, so it remains open.