Oil Pressure Switch Test
- Disconnect pressure hose from pump. Connect Adapter (MB991217 on turbo or SOHC models, and MB991548 on non-turbo or DOHC models) to pump outlet. Connect Adapter (MB990994 on turbo or SOHC models, and MB991549 on non-turbo or DOHC models) to steering gear hose. Connect pressure hoses and Pressure Gauge (MB990662). See Figure . Start engine, bleed air from system and turn steering wheel several times with vehicle not moving until power steering fluid temperature reaches about 122-140°F (50-60°C).
- Disconnect the oil pressure switch connector. Connect an ohmmeter between the oil pressure switch terminal and ground. Slowly close shutoff valve of pressure gauge. As hydraulic pressure increases, check oil pressure switch activation pressure. Refer to the HYDRAULIC PRESSURE SPECIFICATIONS table.
- Slowly open shutoff valve. As hydraulic pressure decreases, check oil pressure switch deactivation pressure. See the HYDRAULIC PRESSURE SPECIFICATIONS table. Replace power steering oil pressure switch if values are not as specified.