Most of the photos on this web page show the custom gauge faces lit with the factory light bulbs. Typically, these are a 194 sized bulb. In some clusters (namely, the 1993-1997 Probe, Contour/Mystique, 1999-2004 Mustang, & 2005 and Up Focus) a smaller bulb is used.
The gauge faces pictured on this web site do not light up by themselves (i.e. Electro-Luminescent). Instead, they rely on the factory incandescent lamps for illumination. The down side is that the factory lighting inside the clusters is hardly consistent due to the amount of obstacles inside the cluster. The OEM manufacturers made up for this by essentially painting the backs of the gauge faces to block some of the light in some areas instead of adding lamps.
On some of the night photos of the gauge faces, you will see two different versions. We have tried to depict the cluster lit with both the factory bulbs and a set of white LED bulbs. The benefit of the white LED bulbs is that they do provide a whiter light, which is nice if you would like the faces to light up white. They also burn cooler, are less susceptible to shock & vibration and draw less current than their incandescent lamps. The downside of the LED bulbs is that their light pattern is not like an incandescent lamp, in the fact that they give off light in a very directional pattern, similar to a flashlight beam. If you would like your gauge faces to light up white at night, we suggest the use of the white LED bulbs, as the standard bulbs can only produce a yellowish light.
Colored LED bulbs can be used to create a very vibrant color scheme, but please keep in mind that if you use all red LED bulbs in the cluster, everything will light up red. Same thing with the use of blue LED bulbs, everything will light up blue, including any warning areas like the redline on the tachometer (if equipped). Often the use of a blue LED bulb with a set of faces that are set up for white lighting, the warning areas (which will have a red filter in that areas) will most likely not light up at all due to the fact that the blue LED will not produce any light in the red wavelengths. The red filter will filter out everything that is not red and those areas will not light up.
Personally, we have not seen a drop in replacement LED bulb that lights up as consistently as an incandescent lamp. The use of LED bulbs results in a gauge faces that does technically light up, but will most likely have bright, or "hot" spots on the face. If this is not an issue, then LED bulbs might be a worthy substitution.
We have done some experimentation with LED bulbs in most of the clusters. For instance, the logo at the top of this page was lit with an array of white LED bulbs. LED bulbs work well in some clusters, but not so well in others. There are a large number of variables to determine whether an LED bulb will work well in a cluster. A major factor is the distance of the LED bulb from the back of the gauge faces. Since most LED bulbs have an LED at the tip, the area that is brightly lit is determined by the distance from the LED to the gauge face and the viewing angle of the LED. LED bulbs with an array of smaller LEDs that fire outward seemed to work well.
We have done some recent experimentation with a LED ribbon inside the cluster. Now, this is more expensive than the drop-in LED bulbs, but the lighting quality that can be achieved is far superior.
Please see the three attached photos of the same set of gauge faces with three different lighting methods.