Component Testing Procedure
Disconnect the ohmmeter; connect pin 3 using a fused (10A) jumper to 12V DC power and pin 1 to ground. Measure the voltage between pin 3 and pin 1 while rotating the thumbwell from full illumination to no illumination. If the voltage smoothly decreases from near 12 volts to near 0 volts, the illumination dimmer is okay. If not, replace the instrument panel dimming module.