P0551
DTC P0551 POWER STEERING PRESSURE SENSOR/SWITCH CIRCUIT RANGE/PERFORMANCEComponent Location:
COMPONENT LOCATION
GENERAL DESCRIPTION
The power steering system increases steering performance and improves steering feel and power-saving effectiveness. The power steering pressure switch senses the power steering load and converts it into a voltage (high/low) signal to the PCM. The PCM then controls the idle speed control motor by using the voltage signal from the power steering pressure switch.
DTC DESCRIPTION
If a power steering pressure switch signal to the PCM is ON when the enable conditions are met, the PCM determines that a fault exists and a DTC is stored.
DTC Detecting Condition:
Schematic Diagram:
MONITOR SCANTOOL DATA
1. Ignition "OFF"
2. Connect Scantool and Engine "ON"
3. Monitor the power steering signal parameter on Current Data.
Specification:
While not turning steering wheel: "OFF"
While turning steering wheel slowly: "ON"
4. Is the ISC ACTUATOR DUTY parameter within specification?
YES: Fault is intermittent caused by poor contact in Fuel Level Sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "W/Harness Inspection" procedure.
TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Power Circuit Inspection" procedure.
POWER SUPPLY CIRCUIT INSPECTION
1. Check Voltage
1. Ignition "OFF"
2. Disconnect Power steering pressure switch connector.
3. Ignition "ON" & Engine "OFF"
4. Measure voltage between terminal 1 of Power steering pressure switch harness connector and chassis ground.
Specification: Approx. 12 V
5. Is the measured voltage within specifications?
YES: Go to "Component Inspection" procedure.
NO: Go to "Check for short to ground in harness" as below.
2. Check for short to ground in harness
1. Ignition "OFF"
2. Disconnect Power steering pressure switch connector.
3. Measure resistance between terminal 1 of Power steering pressure switch harness connector and chassis ground.
Specification: Infinite
4. Is the measured resistance within specifications?
YES: Go to "Check for open in harness" as below.
NO:
- Check for short to ground in harness.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
3. Check for open in harness
1. Ignition "OFF"
2. Disconnect Power steering pressure switch connector.
3. Measure resistance between terminal 1 of Power steering pressure switch harness connector and terminal 12 of PCM harness connector.
Specification: Approx. below 1 Ohms
4. Is the measured resistance within specifications?
YES:
- Substitute with a known - good Power steering pressure switch and check for proper operation.
- If the problem is corrected, replace Power steering pressure switch and go to "Verification of Vehicle Repair" procedure.
NO:
- Check for open in harness.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Ignition "OFF"
2. Disconnect Power steering pressure switch connector.
3. Measure resistance between terminal 1 of Power steering pressure switch harness connector and chassis ground while turning power steering wheel slowly.
Specification: Approx. below 1 Ohms
4. Is the measured resistance within specifications?
YES:
- Substitute with a known - good PCM and check for proper operation.
- If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
NO:
- Substitute with a known - good Power Steering Switch and check for proper operation.
- If the problem is corrected, replace Power Steering Switch and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness tests have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time