Volvo: 1993 Volvo 940 headlight failure, volvo 940 wagon, dashboard lights

Question
I have a 1993 Volvo 940 wagon which I recently replaced the stock stereo with a new one.  Not immediately following, but shortly thereafter, the headlights stopped working.  The parking lights and dashboard lights work when the headlight switch is in the parking light position.  However, once it is turned to the headlight on position the dashboard lights and the parking lights both go out and the headlights do not turn on.  I thought it might be the switch itself, so I just replaced it with a brand new one.  I have inspected every fuse and all of them are in working order.  I am unfamiliar with the relays and cannot find a diagram of them anywhere.  Why will my headlights not turn on?  Thank you very much for your time and any assistance you are able to give me.

Justin Padiak

Answer
Justin,
I would check over your work to see if somehow you tapped into the headlamp wires. In the relay box there is a relay for the day time running lights. It is one of the small "J" relays. They should all be the same so you can swap them back and forth. Turn over the relay box and make sure that all the wires are tight.