This is a very hard climb, starting in Monthey (422m) and sharing the same road as to Pas de Morgins (1370m, road height 1378m) until shortly before Morgins (1311m) at Arche (1254m). Here an unsigned very narrow tarmacced road winds its way up to the pass toward the north. Shortly before the pass (you will know where when you arrive there) you should take off north again on another small road for the last little stretch up to the pass.

One could also arrive here from Morgins on a road that is almost single-lane (very, very narrow) and it starts with gradients above 20% out of Morgins and you gain 387m in altitude in 2.77 km (14.1% on average) before a short descent and the crossroad with the other road to the pass. The road is also asphalted on the northern side up from Collombey-Muraz (403m), but the road is formally closed due to risks of landslides, but I believe it is passable. The northern climb should be quite hard too, but I have only descended part of it.