Q The digital display in my 1998 model car has slowly dimmed to unreadable over the years. What the heck is causing this and how do I fix it?
A This is a common issue with older cars that have LED-based gauge clusters. The problem is one of chemistry, not electronics. The light-emitting diode is a type of display-system-electronics element that can be arranged in low-resolution pixel format to show information to the driver. Unfortunately, LED displays from the 1980s into the 2000s were not as good as what we have today. Over years and years of thermal cycling, the chemistry in the diodes breaks down, and the result is dwindling light output. This low output is worse on hot days; on cold days part or all of the readout might work again.
A temporary solution would be to replace some resistors in the instrument cluster to increase the voltage to the LED panel, but that would result in accelerated failure of the remaining good pixels. Your only solid fix is to have an aftermarket repair house install a new LED panel or get a new old stock part, which means the entire gauge cluster. The former is cheaper than the latter if you can find a good shop, but there’s really no way to fix this yourself.