Bench Testing

First remove switch. Refer to ACCESSORY SWITCH BEZEL .
With switch removed from vehicle, use a jumper wire and connect a 12 volt supply to Pin 1 and 2. Using a third jumper wire, ground Pin 3. Refer to (Fig 1 ) and the Rear Window Defogger Switch and Harness Connector Pin Call-Out table.

Fig 1: Identifying Rear Window Defogger Switch Connector
Courtesy of DAIMLERCHRYSLER CORP.
Follow the same procedures used for IN-VEHICLE TESTING, except for Step 2.