Replace pass side headlight bulb on Volvo '02 S40

Sounds like you need to replace the bulb.

Possible bad relay or bad ground. Try tapping the relay with helper watching to see if light flashes.

Mode actuator bad

There will be a drain plug in the bottom of the Radiator so you can drain the old Coolant out. Close the drain plug and refill from the Coolant Tank on the inner fender well. Fill it with the engine off then start it up and finish filling to the full line on the coolant tank.

better just to replace them you could damage the others taking them out

Remove coolant reservoir and washer fill tube. Turn and pull tube to remove. This will give access to headlight bulbs.

Ok, this is a bad motor and you will have to replace this failed motor. this will fix the issue.

headlamp bulb access cover is a good description. I'd start there.

Sounds like a wire to me. It's definitely not fuses (unless the fuses have been split for left and right hand side which I have never come across, but we are talking about volvo lol) so I'd say most likely there'd be a break somewhere in the harness. The driver's side probably blew as all the power gets sent to one side when one bulb isn't working - so it's working twice as hard usually - making it more susceptable to blowing.

possibly a worn headlight relay also check housing for cracks/leaks