so on my 91 740 turbo the left front healight(as if u are sitting in the car) is much brighter than the right side. when i switch the bulbs it doens't make a difference. i checked te power going to each set of lights and the one on the left is like 11.63V and the right side is 11.43V. is this enought difference to make one side appear VERY dim(@ night it looks as if it is barely on). when i hit the brights they are both the same but when norm lights are on the left is much brighter. i would like to change these to the euro lights sytle but am wondering if i can use my current wiring for that and if the new euro lights would have the same affect of one being brighter or if it would be another way for me to fix this prob.

thx

mike

As some one suggested , it may be the ground. The voltage difference you see would not make much difference in brightness.

With the lights on,

Test one:measure across the bulb, ie put one voltmeter probe on the plus side of the bulb connector and the other on the ground side of the connector. Measure right at the bulb!

Test 2: measure the voltage on the ground side ,ie probe on ground wire, other probe on battery negative.

I suspect you will notice more voltage across the bright lamp ( test one), or more voltage on the ground side of the dim one (test two).

Double check the lamps and make sure one of them doesn't have a small rock chip in it. A very light layer of road film can find its way in and severely dampen the lights ability although often barely visible from simple observation. Start simple, swap the lights side to side and see if there is a constant.

Leonard

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.

Mike: go to: "www.vclassics.com/archive/relays.htm" for a fine analysis of lamp brightness, wiring, relays, DIY. etc. (You just missed the 'thread' on this, with a direct link to that site, but try 'the above'.) --PD.