P0501
P0501Component Location:
General Description
A Wheel Speed Sensor (RF) is used by the ECM/PCM to calculate vehicle speed. This sensor is connected directly to the ECM in non-ABS vehicles. On ABS vehicles, the sensor feeds the ABSCM first; the signal is then sent to the ECM/PCM.
DTC Description
If the vehicle speed signal is below 0.62 MPH during 2 sec under enable conditions, PCM sets P0501.
DTC Detecting Condition:
Signal Waveform:
Schematic Diagram:
Monitor Scantool Data
ABS Vehicle
1. Connect scantool to Data Link Connector (DLC).
2. Warm up the engine to normal operating temperature.
3. Monitor the "VSS" parameters on the scantool. (ENG. Control)
4. Monitor the "WHEEL SPEED SENSOR-FR" parameter on the Scantool. (ABS Control)
5. Are the parameters displayed correctly?
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 go to "Verification of vehicle Repair" procedure.
NO
- If both vehicle speed signal from ECM and Wheel Speed Signal from ABS on current data are not displayed refer to DTC C1203 "Wheel speed sensor front -RH open/short" in ABS DTC section.
- If the Wheel Speed Signal from ABS is O.K but Vehicle Speed Signal from ECM on current data is not properly displayed, go to "Inspection and Repair" procedure.
Non-ABS Vehicle
6. Connect scantool to Data Link Connector (DLC).
7. Warm up the engine to normal operating temperature.
8. Monitor the "VSS" parameters on the scantool.
9. Are the parameters displayed correctly?
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 go to "Verification of vehicle Repair" procedure.
NO - Go to "W/Harness Inspection" procedure
Terminal and Connector Inspection
ABS Vehicle
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 "Signal Circuit Inspection" procedure.
Non-ABS Vehicle
4. 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.
5. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination,deterioration, or damage.
6. 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
Non-ABS Vehicle
1. Key "ON".
2. Measure voltage between terminal 1/E50 of the wheel speed sensor harness connector and chassis ground. (Connect wheel speed sensor connector)
Specification : Approx. B +
3. Is the measured voltage within specification?
YES - Go to "Signal Circuit Inspection" procedure.
NO - Repair open or short to ground in harness, and go to "Verification of Vehicle Repair" procedure.
Signal Circuit Inspection
ABS Vehicle
1. Check short to ground in harness
1. Key "OFF".
2. Disconnect PCM connector.
3. Disconnect ABS control unit.
4. Measure resistance between terminal 20/C01-1 of PCM harness connector and chassis ground. [A/T]
Measure resistance between terminal 64/C01 of ECM harness connector and chassis ground. [M/T]
Specification : Infinite
5. Is the measured resistance within specification?
YES - Go to "Check open in harness" as follows.
NO - Repair short to ground in harness, and go to "Verification of Vehicle Repair" procedure.
2. Check for open in harness
1. Key "OFF".
2. Disconnect PCM connector.
3. Disconnect ABS control unit.
4. Measure resistance between terminal 20/C01-1 of PCM harness connector and terminal 3/E51 of ABS control module harness connector. (A/T)
Measure resistance between terminal 64/C01 of ECM harness connector and terminal 3/E51 of ABS control module harness connector. (M/T)
Specification : Approx. below 1 ohm
5. Is the measured resistance within specifications?
YES - Go to "Component inspection" procedure.
NO - Repair Open circuit and then, go to "Verification of Vehicle Repair" procedure.
Non-ABS Vehicle
3. Check short to ground in harness.
1. Key "OFF".
2. Disconnect PCM connector.
3. Disconnect wheel speed sensor connector.
4. Measure resistance between terminal 2/E50 of wheel speed sensor harness connector and chassis ground.
Specification : Infinite
5. Is the measured resistance within specifications?
YES - Go to "Check open in harness" as follows.
NO - Repair short to ground in harness, and go to "Verification of Vehicle Repair" procedure.
4. Check open in harness
1. Key "OFF".
2. Disconnect PCM connector.
3. Disconnect wheel speed sensor connector.
4. Measure resistance between terminal 60/C01-2 of PCM harness connector and terminal 2/E50 harness connector.
Measure resistance between terminal 79/C01 of ECM harness connector and terminal 2/E50 harness connector.
Specification : Approx. below 1 ohm
5. Is the measured resistance within specifications?
YES - Go to "Component inspection" procedure.
NO - Repair Open circuit and then, go to "Verification of Vehicle Repair" procedure.
Component Inspection
ABS Vehicle
1. ENG "ON".
2. Measure signal waveform of Vehicle Speed from ABS to ECM while driving.
Specification :
3. Is the signal waveform normal?
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.
NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others
NO - Substitute with a known - good ABS control unit and check for proper operation. If the problem is corrected, replace ABS control unit and go to "Verification of Vehicle Repair" procedure.
Non-ABS Vehicle
4. Engine "ON".
5. Measure signal waveform of wheel speed sensor while driving.
Specification :
6. Is the signal waveform normal?
YES - Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure.
NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others
NO - Substitute with a known - good wheel speed sensor and check for proper operation. If the problem is corrected, replace wheel speed sensor 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. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.