A terminal inspection

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

Measure the wave pattern of the A terminal on the panel light control switch using an oscilloscope.
Set the headlight switch to either the first or second position.
Set the panel light control switch to the brightest position.

Fig 1: Measuring Wave Pattern On Panel Light Control Switch Using An Oscilloscope
Courtesy of MAZDA MOTORS CORP.
Verify that the pattern on the screen is as shown in the figure.

Fig 2: Identifying Panel Light Control Switch Wave Pattern On Screen
Courtesy of MAZDA MOTORS CORP.
Verify that the pattern on the screen matches the pattern shown in Fig 3 as the panel light control switch is gradually turned to the darkest position.

Fig 3: Identifying Panel Light Control Switch Wave Pattern
Courtesy of MAZDA MOTORS CORP.