Oil Pressure Switch
- Disconnect pressure hose from pump and connect Adapters (MB991217-A to pump outlet; MB990994 to steering gear hose), Pressure Hoses (C-4535) and Pressure Gauge (C-3309-E). 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 oil pressure switch connector. Connect ohmmeter between oil pressure switch terminal and ground. Slowly close shut-off valve of pressure gauge. As hydraulic pressure increases, check pressure that activates switch. See HYDRAULIC PRESSURE SPECIFICATIONS table.
- Slowly open shut-off valve. As hydraulic pressure decreases, check pressure that deactivates switch. Refer to the HYDRAULIC PRESSURE SPECIFICATIONS table. Replace power steering oil pressure switch if values are not as specified.