A question before I delve in......

[MiniNinjaRob]

My drivers door switch - the one that turns the interior lights on and off - doesn't work. All the other switches do, but the drivers one doesn't turn the lights on when you open the door.
Do I just need a replacement switch? Are they easy to fit?
Can it be any other problem? I will pull it out and see if the connections are dodgy first.

[NI_Volvo_Nut]

When you take it out you will see the contact, it just needs cleaned.

[MiniNinjaRob]

OK I took the switch out and tested it. When I test continuity across the connections its OK but when I connect it up it doesn't work.
However I did notice when I brushed one of the wire ends against the bodywork the interior lights came on.
Correct me if I'm wrong but does that mean the switch actually makes a connection to ground when it is activated (eg released in this case)? If this is true then I assume the connection within the switch which connects to the mounting hole (ground) has broken so I need a new switch.....

Is that right?

[Laird Scooby]

Chances are the connection to ground/earth through the screw is just dirty/rusty. It's a 2-contact switch, when it is made (plunger out) both contacts go to earth but are obviously linked together. Usually one does the normal interior light and the other operates the delay part.

Make sure the plunger hasn't been rotated (it has a function where if you push it in and turn it slightly clockwise, it will latch off) so that if you need to, you can work on something with the door open or leave the door open perhaps to hear the radio during a roadside picnic or whatever without the interior light running the battery down.

If you remove one of the other pillar switches, you'll see the difference in them and the above will make more sense.

[MiniNinjaRob]

Originally Posted by Laird Scooby

Chances are the connection to ground/earth through the screw is just dirty/rusty. It's a 2-contact switch, when it is made (plunger out) both contacts go to earth but are obviously linked together. Usually one does the normal interior light and the other operates the delay part.

Make sure the plunger hasn't been rotated (it has a function where if you push it in and turn it slightly clockwise, it will latch off) so that if you need to, you can work on something with the door open or leave the door open perhaps to hear the radio during a roadside picnic or whatever without the interior light running the battery down.

If you remove one of the other pillar switches, you'll see the difference in them and the above will make more sense.

I cleaned all the metal parts and the screw and the bit of the bodywork it screws into anyway as I thought it might be an earth issue and it didn’t make any difference. There wasn’t any continuity between the metal bit that touches the bodywork via the screw and the main contacts so it looks like something has gone wrong in the switch.

Thanks for the help all.

[Forrest]

It is possible (in fact quite easy) to dismantle these switches and clean the contacts inside. They look more complicated than they really are because they have two circuits which make to ground. One for the interior lamp and another one for the alarm. That said replacement switches are readily available and quite cheap if you don’t fancy fiddling about.

[Clan]

Originally Posted by Forrest

It is possible (in fact quite easy) to dismantle these switches and clean the contacts inside. They look more complicated than they really are because they have two circuits which make to ground. One for the interior lamp and another one for the alarm. That said replacement switches are readily available and quite cheap if you don’t fancy fiddling about.

if the switch has two terminals ( some have ) try the other one , otherwise best get a new switch , they will always fail again later . I fitted a second hand one on another car of mine in 1987, after 230,000 miles it's now failed like yours .

[MiniNinjaRob]

Considered taking it apart but got a new one off eBay for £7 delivered (not a Volvo part but should be fine) which is waaaaay easier.

[MiniNinjaRob]

Just as an update - £7 part from eBay did the trick and the interior lights are working 100%.

[Laird Scooby]

Great news!