Test 3: Interior Central Locking Switch (SL500)

Turn ignition switch to LOCK position. Disconnect Pneumatic System Equipment (PSE) control module. Using Harness Adapter (202 589 16 63 00), connect Breakout Box (129 589 00 21 00) to PSE control module harness connectors. Measure voltage between ground and terminal No. 48 at breakout box. When interior central locking switch is pressed to LOCK position, battery voltage should exist. When interior central locking switch is pressed to UNLOCK position, battery voltage should exist with opposite polarity. When interior central locking switch is not pressed, less than one volt should exist. If voltage is as specified, interior central locking switch is okay at this time. If voltage is not as specified, check wiring. See WIRING DIAGRAMS . If wiring is okay, suspect faulty interior central locking switch.