What year is your car? What model? Is it a turbo or na? Have you checked the harness and all wiring in the engine compartment? Have you replaced the bulb on the low beam that doesn't work or teste dthe light on the opposing side that does work?

More infornation would be useful, but I can tell you that fixing the lights in a 700 is no single step solution. The harnesses on the earlier 700s were made with ecofriendly material that breaks down with time and exposure to the high heat of the engine compartment.

If you replaced the relay and it made a difference, maybe you have a bad socket. Pull the relay, pull the relay board, and make sure the connections that the relay fits into are tight and not shorting out. Also, compare the relay you got from teh dealer meticulously with teh one you had originally. Many relays look almost identical but have wholly different functionality.

Next, open the hood, and trace all the wiring for the head lights. Specifically, you are looking for crumbling plastic protection that allows wires to rub and short. Look at the wiring anywhere it is openly exposed, and cut the black sheathing back about 2" if its crumbling up into the sheathing until you get to good wiring.

If you find any bad wiring clean it up with your hands and a small wire brush, and then reseal it with electrical tape. In fact, I would do this with ALL the engine wiring while your at it. If you find really bad stuff cut it out with wire cutters and replace it with a solid splice job.

If it still doesn't work your problem is probably the one I had with mine. Over time, the connectors that hook onto the lights (at the end of the wires) become oxidized on both the male and female sides of the connection. Even the SMALLEST oxidation can effect the current to the lights. I would suggest going to a junkyard and looking for some that are new looking, cutting them out where needed, and taking them home for your brick. It took a LOT of effort for me to finally realize just how little oxidation can effect the lights on these cars and get mine working properly again. You might also use a screwdriver to bend the female metal connectors of the wires a little and tighten them up... sometimes they can be just loose enough to reduce current flow and cause the lights to fail.

Good luck,
Rick