Inspect the crimped butt connector
WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
If the butt connector has been correctly crimped both crimping points should be uniformly compressed.
All cables should be crimped in place towards the center of the butt connector and not displaced towards the ends.
Pull the cables to ensure that none are loose.