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Home >> Mitsubishi >> 1998 >> Montero >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> DTC Tests >> DTC P0551: Power Steering Pressure (PSP) Sensor Circuit Performance
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DTC P0551: Power Steering Pressure (PSP) Sensor Circuit Performance

NOTE: For terminal identification, see TERMINAL IDENTIFICATION . For circuit and wire color identification, see WIRING DIAGRAMS article.
  1. Using scan tool, read Power Steering Pressure (PSP) status (item 27). Switch status should read ON when steering wheel is turned. If switch status is as specified, fault is intermittent. See INTERMITTENT DTCS . If switch status is not as specified, go to next step.
  2. Disconnect pressure hose from oil pump. See Fig 1. Install Adapter (MB990993 or MB991217 ) on oil pump. Install Adapter (MB990994 ) on disconnected hose. Connect Pressure Gauge (MB990662 ) and shutoff valve between adapters. Open shutoff valve. Bleed steering hydraulic system. See HYDRAULIC SYSTEM BLEEDING in STEERING SYSTEM - POWER RECIRCULATING BALL article.
    Fig 1: Testing PSP Sensor Circuit
    G97B06408Courtesy of MITSUBISHI MOTOR SALES OF AMERICA
  3. Install a thermometer in fluid reservoir. Start engine and allow it to idle. Turn steering wheel several times until fluid temperature reaches 122-140°F (50-60°C). Disconnect PSP switch connector. Install a DVOM between ground and PSP switch terminal. See Fig 1. Note continuity reading on DVOM. Go to next step.
  4. With engine idling, gradually close shutoff valve to increase power steering system pressure. Check pressure when PSP switch is actuated by watching for a change in continuity. PSP switch should be actuated when pressure is 218-290 psi. Gradually open shutoff valve to decrease pressure. Check pressure when PSP switch is de-actuated. PSP switch should de-actuate at 102-174 psi. Turn engine off. If PSP operates as specified, go to next step. If PSP does not operate as specified, replace PSP switch. Go to step 8).
  5. Disconnect PSP switch connector. Turn ignition on. Using DVOM, check voltage between ground and PSP switch connector terminal No. 1. If battery voltage exists, repair or replace PSP switch connector as necessary. Go to step 8). If battery voltage does not exist, go to next step.
  6. Check wiring harness between PSP switch and PCM. Repair wiring harness as necessary. Go to step 8). If wiring harness is okay, go to next step.
  7. Inspect PCM connector for damage. Repair or replace connector as necessary. Go to next step. If connector is okay, replace PCM. Go to next step.
  8. Using scan tool, read Power Steering Pressure (PSP) status(item 27). Switch status should read ON when steering wheel is turned. If switch status is as specified, test is complete. If switch status is not as specified, road test vehicle and attempt to duplicate conditions that caused original complaint. Recheck for DTCs. If no DTCs are displayed, test is complete.
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