V40: headlights

[fox1uk]

Hi peeps
I need help as Mot is looming and I do not know what to do . My headlights are dim all the time but I can use full beam, So my headlights as such do not work. I have looked around the forum and I feel it could be the Cem. So is it a replacement part of it like a light bulb(does it have a diagram ) or once that has gone do you need to replace all. As you probably can see I am new to this and I am lost for ideas?

[aldred309uk]

Are the dipped beam bulbs dull or not illuminating? There are side light bulbs and dipped beam too. What age is your car?

[CharlesStevenson]

Have you checked the obvious, have the 2 dipped beam bulbs blown?

I ask because I thought I had a CEM issue with my new V40 this weekend but it was simply a blown dipped beam bulb?

Assuming, however, that you've checked that, have you had the car long and has this been an issue before?

I ask because often a previous owner has 'bodged' a faulty CEM by splicing wiring from one light unit to the adjacent one & you'll tell this by pulling off the rubber covers.

Also is it BOTH dipped beams NOT working or is one / both simply very dim?

It's because they can be due to different causes.

Assuming again that this isn't so, then yes, you may have a CEM issue, but don't worry since it's (probably) fixable.

A quick check (that's worked for me) is to remove the trim panel below the steering wheel and you'll see the CEM unit next to the bonnet release (It's the big white box).

With the ignition on, when you switch on the lights you should hear, and if you put your fingers on the box, feel, a relay switching on to energise the higher voltage to the lights.

You should also feel the same when you flick to main beam (there are 5 relays in the box).

What you can then try to do is to whack / tap / hit the box & see if that forces the relay inside to work. Yes, it sounds odd but it worked for me to prove that the relay for one dipped beam on my old S40 was dying.

Here's a link to my post about this ...

https://www.volvoforums.org.uk/showthread.php?t=272600

That being so, it's quite possible to take the unit apart and solder in a new relay.

The relays are cheap but make sure you've got a good soldering iron & both a desoldering pump and desoldering webbing as you'll need them to get the dead relay out.

... or you can buy a 2nd hand unit from ebay, but where's the fun in that?!?!

HTH but post back if you want more or clearer info

[CharlesStevenson]

A suggestion, which will infuriate some on here but ... if it's on why not turn off your daytime running lights?

Yes, you'll not be seen in traffic as easily, but you won't be running your bulbs as much so will possibly add more life to the circuit once repaired.

{Ducks for cover in garage pit}