first, heck for voltage to ground at the dim headlight. A single dim headlight is often caused by a bad ground connection. The wattage at the light is equal to voltage squared divided by the resistance, so the voltage at the light has a significant effect on the out put of the light. Most cars, including Volvos lose a significant amount of voltage in the wiring, switches and relays in the interior of the car. Installing headlight relays which supplies alternator output voltage directly to the headlights will brighten both headlights. Make sure your ground connections are good, too. You can also install a relay to operate the fog lights if your car is so equipped.

All three of our 740Ts have the headlight relays and it significantly improves the output of the stock 55/60 watt headlamps.