♔♔♔ The following Wiring Diagram applies for Volvo S40 and V40 2004 models. Herein you will find detail information about the electrical specification, features, maintenance, and service procedures. Every component has a component designation consists of two parts. The first part is a type number that describes the type of component in question, for example 3/xx. The second part of the designation is a serial number, for example, x/2.