I had the same problem...and I eventually solved it by replacing the connector and the lamp socket.

It begins with a small amount of corrosion. As n0v8or pointed out to me, corrosion causes increased resistance which in turn causes heat. As the situation worsens, the corrosion breaks contact (often restored by wiggling the socket). At some point, the heat actually begins to melt the connector....and the lamp socket. This is what happened in my case.

You can ring this up as another component-level light-socket volvo-ism.

If you buy new connectors, you'll also have to order the wire with female connector ends. These snap into slots in the gray connector body. In my case, my indy shop pulled intact connectors from his used parts inventory. I bought new lamp sockets at a Volvo dealer. (Since both socket and connector warped together, they'd fit each other. But they wouldn't fit onto perfectly shaped replacement parts.)

Before connecting, I sprayed the connections with tri-flow and applied a little dielectric grease (these steps to repel moisture). Then I wrapped the connection with electrical tape - another moisture barrier.
--
(98 S70 T5SE misc mods, mostly lighting) (92 940GLE)

Yup,

Same problem here.

Theres a clip that holds the bulb in that works its way loose. They wiggled my wire for a few visits and then bent the clip when I started to complain more. Finally after about 6 times bringing it in I got rather hostile with them and they finally did "something" and fixed it. My lights have been working for a year now and have not gone out. I could go under there and look but Im afraid to even touch the front of my car for fear they will start going out again.

I at first just thought it was a burnt bulb, so I bought new ones, trying to get a yellow h1 that's really yellow is tough. Worked fine for 2 weeks then the right one was out again. Took it out, put it in, worked again. Tried the old bulb, it worked too! It's gone out once since then, and with a little jiggling it comes back on.

So, no solution for you, but I'm right there with you!!

-Ananda

98 S70 T5SEM

When you say a twist to the assembly, do you mean the lgiht fixture or the connector assembly?

A few thoughts come to mind.

1) are your lamps old? perhaps there's a little corrosion fouling the connection where the H1's fit into the assembly. new h1's, a litle emery cloth, and an application of tri-flo (or other electrically conductive synthetic lubricant/protectant) should do the trick.

2) are the wires coming to the the connector flexible? brittle? cracked?

3) you say a twist to the assembly...these lights twist in. is the mechanism failing to lock? are you twisting until it clicks into place?