Tech Tip: Dash Light Switch

The interior dash light switch for the 1955-57 Thunderbird is located on the headlight switch. The interior dash lights are turned on by pulling out on the headlight switch. At least that is the theory. This "tech tip" is a simple test. If your dash lights do not work when you pull out on your headlight switch, the problem may be that your switch has developed a thin layer of oxidation. The lights are turned on when a small spring tip comes in contact with the inner mechanism of the switch. As you turn your switch from left to right your lights will dim or brighten. This is due to increasing or decreasing the tension on the spring. The greater the tension, the greater amount of contact is made by the spring. This increased contact allows more current to flow through the switch creating a brighter light display on your dash. As oxidation builds up on the spring contact, a failure to make contact can result. No contact means no dash lights. As most veteran Thunderbird owners have discovered, if you simply turn your switch from left to right a few times, you can cut through enough of the oxidation to make contact again with the spring. Your lights will now work. Sometimes, a few turns are not enough. As I was having problems with my switch, I called our resident "Guru", Mr. Ken Smizinski. He asked me if I had turned the switch a few times. I replied that I had turned the switch three or four times with no results. Ken proceeded to tell me that it may take a dozen or so rotations of your switch before contact can be restored. Sure enough, after further effort my switch was restored to standard operation.

The oxidation of our dash switches is the result of infrequent use. Most of us rarely drive our cars at night. If we do drive at night, our nights are limited to those hot summer evenings when there is not even a hint of rain in sight. The replacement switches available from the parts supplier appear to be more prone to oxidation than the original switches. As such, inspect your switch closely before deciding to replace it because your interior lights no longer work. The solution may be as simple as a few twists of your hand.

Source: CTCC Tech-Tip Manual 1993-1997