With the aid of an ohmmeter, measure the ohmic resistance between terminals 2, 5 and 1 at ambient temperature, the values should be close to those shown in the table below.
Resistance Terminal in Ohm
2 to 5 7.5KΩ to 12KΩ
5 to 1 7,5KΩ at 12 KΩ
1 to 2 00000.0 KΩ
