The following wiring diagram and cable harness applies for Volvo S40/V50 for 2004 models. In this manual you will find detail description and explanation of each electrical components installed on the vehicle such as battery (relay of rear window, horn, climate control system, fog lights, high beam, windshield washer, etc), ignition switch (switch unit for cruise control system, hazard warning flasher, power sunroof, etc), combustion preheat module, driver information module, wiper motor module, electromagnetic clutch and climate control system, etc.
General recommendations prior to working with the electrical system and wiring harness:
- Be especially careful when working on or around SRS, SIPS, and IC components.
- Make sure that no wires are pinched, frayed, or pierced.
- Never install accessories by the sensors.
- Where applicable, work on the steering wheel, steering shaft, or steering gear must be done in accordance with the methods in the SRS section of VADIS.
- Certain components of the aforementioned systems must be grounded while working. Read the appropriate sections in VADIS.
- Install no accessories in the areas between the A and B posts, the B and C posts, and the C and D posts.
Find more information about Volvo S40/V50 Wiring Diagram (2004) here (217 pages of pdf file docs. PASS: wiringdiagrams21.com)