Try bypassing the dimmer switch, to see if the lights come on. I expect you'd do this by using a small jumper wire with alligator clips at each end (build it yourself with about $2 parts from Radio Shack), or unplugging the appropriate wires and connecting them directly to close the circuit.

FIRST, though, I'd make sure the ground to the circuit or the dimmer didn't get disturbed. In Volvos the ground is usually a black wire (or sometimes a black-and-color wire). One way to test this is by jumping the ground contact directly to a reliable ground using the same jumper wire described above. (My home made jumper wire is 6' long - I made it the second day we owned our first Volvo. That, and at minimum a digital $25 electrical meter, are essential to owning a used Volvo.)

Do you have a wiring diagram? If not, get the Haynes manual (ugh) or search for brickboard correspondent n0v8or and send him an email. He's an automotive electrical design engineer, and has been able to send me very helpful electrical advice (along with diagrams).
--


David
1998 S70 T5SE // misc mods (mostly lighting) // red calipers
1992 940 GLE // Hella Micro DE foglights and 170K