Hi.
Buy the "Haynes Service and Repair Manual", it covers all brake system in chapter 9, there is furthermore a electrical wiring diagram in chapter 12.25, covering the brake system warning light.
The Garage i use, uses a computer program called "merkonomen", it covers all repairs and diagrams for the Espace, and that is even the Matra model never was imported to Denmark. A modern garage, has no problem in finding the diagrams, the program is mostly delivered by the part supplier.
Good Luck.
Jensen.