Power Steering Pressure (PSP) Switch

On some applications, PCM receives signal voltage from PSP switch indication that the power steering pressure exceeded a specific limit. The PCM uses the PSP switch signal to adjust idle speed to compensate for additional engine load. If the PSP switch fails with closed contacts, line pressure will be slightly high, causing firm engagements, firm shifts, and harsh coast down shifts. If the ACC switch fails with open contacts, line pressure will be slightly low during increased power steering load.