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Home >> Mitsubishi >> 2002 >> Lancer LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0551: Power Steering Pressure Sensor Circuit Range/Performance >> Diagnostic Procedure

Diagnostic Procedure

CAUTION: To prevent damage to scan tool, always turn ignition switch to LOCK position before connecting or disconnecting scan tool.
  1. Connect scan tool to data link connector. Start and operate engine at idle. Set scan tool to the data reading mode for data list item 27: POWER STEERING PRESSURE SWITCH. If steering wheel is not turned while idling, OFF will be displayed. If steering wheel is turned while idling, ON will be displayed. If sensor is operating properly, malfunction is intermittent. If sensor is not operating properly, go to next step.
  2. Do not disconnect PSPS switch harness connector. Start and operate engine at idle. Using a DVOM, measure voltage between ground and PSPS sensor harness connector terminal No. 1 by backprobing. When steering wheel is not turned, battery voltage should be present. When steering wheel is turned, voltage reading should be one volt or less. If voltage reading is as specified, go to next step. If voltage reading is not as specified, go to step  5 .
  3. Check PSPS switch harness connector for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, go to next step.
  4. Start and operate engine at idle. Set scan tool to the data reading mode for data list item 27: POWER STEERING PRESSURE SWITCH. If steering wheel is stopped while idling, OFF will be displayed on scan tool. If steering wheel is turned while idling, ON will be displayed on scan tool. If sensor is operating properly, malfunction is intermittent. If sensor is not operating properly, replace ECM (M/T) or PCM (A/T). After replacing ECM or PCM, go to step  14 .
  5. Check PSPS harness connector for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, go to next step.
  6. Disconnect PSPS harness connector. Turn ignition on. Measure voltage between terminal No. 1 and ground. Battery voltage should be present. If voltage is as specified, go to step  11 . If voltage is not as specified, go to next step.
  7. Do not disconnect ECM harness connector C-119 (M/T) or PCM harness connector C-118 (A/T). Disconnect PSPS harness connector. Turn ignition on. Measure voltage between ground and ECM harness connector C-119 terminal No. 37 (M/T) or PCM harness connector C-118 terminal No. 52 (A/T) by backprobing. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, go to step  9 .
  8. Check ECM harness connector C-119 (M/T) or PCM harness connector C-118 (A/T) for damage. If connector is damaged, repair or replace as necessary. After repairs, go to step  14 . If connector is okay, repair open circuit in wiring harness between PSPS harness connector terminal No. 1 and ECM harness connector C-119 terminal No. 37 (M/T) or PCM harness connector C-118 terminal No. 52 (A/T). After repairs, go to step  14 .
  9. Check ECM harness connector C-119 (M/T) or PCM harness connector C-118 (A/T) for damage. If connector is in good condition, go to next step. If connector is not in good condition, repair or replace as necessary. After repairs, go to step  14 .
  10. Check for short circuit to ground between PSPS harness connector terminal No. 1 and ECM harness connector C-119 terminal No. 37 (M/T) or PCM harness connector C-118 terminal No. 52 (A/T). If wiring harness is in good condition, replace ECM (M/T) or PCM (A/T). After replacing ECM or PCM, go to step  14 . If wiring harness is not in good condition, repair as necessary. After repairs, go to step  14 .
  11. Replace PSPS. After replacing PSPS, check trouble symptoms and DTCs. If DTC P0551 is output, go to next step. If DTC P0551 is not output, go to step  14 .
  12. Check ECM harness connector C-119 (M/T) or PCM harness connector C-118 (A/T) for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, go to next step.
  13. Check for harness damage between power steering pressure switch harness connector terminal No. 1 and ECM harness connector C-119 terminal No. 37 (M/T) or PCM harness connector C-118 terminal No. 52 (A/T). If wiring harness is in good condition, replace ECM (M/T) or PCM (A/T). After replacing ECM or PCM, go to next step. If wiring harness is not in good condition, repair as necessary. After repairs, go to next step.
  14. Start and operate engine at idle. Set scan tool to the data reading mode for data list item 27: POWER STEERING PRESSURE SWITCH. If the steering wheel is not turned while idling, OFF will be displayed. If the steering wheel is turned while idling, ON will be displayed. Turn ignition switch to LOCK position. If switch is operating properly, inspection is complete. If switch is not operating properly, repeat diagnosis.
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