P0551

DTC P0551 POWER STEERING PRESSURE SENSOR/SWITCH CIRCUIT RANGE/PERFORMANCE

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
The ECM monitors the power steering switch and can determine when the signal is outside of the possible range of the switch. When the signal is out of range for a prolonged period of time, the ECM will set DTC P0551.

DTC Detecting Condition:

Schematic Diagram:

Signal Waveform And Data:

MONITOR DTC STATUS
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Press F4 (DTAL) to select DTC information from the DTCs menu
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
4. Read "DTC Status" parameter
5. Is parameter displayed "History (Not Present) fault"?

NOTE:
- History (Not Present) fault : DTC occurred but has been cleared.
- Present fault :DTC is occurring at present time.

YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

NO - Go to next step as below.

SIGNAL CIRCUIT INSPECTION
1. Check for open or short to ground in signal circuit
1. With ignition "OFF", disconnect the power steering switch.
2. Ignition "ON" & Engine "OFF"
3. Measure voltage between terminal 1 of the power steering switch harness connector and chassis ground

Specification : Approx. B+

4. Is voltage within the specification?

YES - Go to next step as below.

NO - Check for short to battery in signal circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure

2. Check for short to battery in signal circuit
1. With ignition "OFF", disconnect ECM connector
2. Ignition "ON" & Engine "OFF"
3. Measure voltage between terminal 1 of the switch harness connector and chassis ground.

Specification : Approx. 0 V

4. Is voltage within the specification?

YES - Go to next step as below.

NO - Check for short to battery in signal circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure

TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) 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 next step as below

COMPONENT INSPECTION
1. With ignition "OFF", reconnect the switch and ECM connectors
2. Ignition "ON" & Engine "ON".
3. Measure voltage between terminal 1 (back probe) of the switch harness connector and chassis ground.

Specification : Approx. B+
- Signal "OFF" (Steering wheel = Straight ahead) : Approx. B+
- Signal "ON" (Steering wheel = Turned) : Approx. 0 V

4. Is voltage within the specification?

YES - Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure

NO - Substitute with a known-good sensor and check for proper operation. If the problem is corrected, replace sensor and then 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. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History (Not Present) fault"?

YES - System performing to specification at this time. Clear the DTC

NO - Go to the applicable troubleshooting procedure.