P0501
P0501General Description
The Wheel Speed Sensor (WSS) generates a waveform with a frequency proportional to the speed of the vehicle. The signal generated by the WSS informs the PCM not only if the vehicle speed is low or high but also if the vehicle is or is not moving. The PCM uses this signal to control the fuel injection, ignition timing, transaxle shift scheduling and torque converter clutch scheduling. The WSS signal is also used to detect rough road conditions.
DTC Description
Checking signal from wheel speed sensor or ABS control unit. Under detecting condition, if an signal is in the detecting condition for more than 20 sec., PCM sets P0501. MIL (Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition:
Schematic Diagram:
Signal Waveform:
Monitor Scantool Data
1. Ignition "OFF"
2. Connect Scantool and Engine "ON"
3. Drive vehicle in gear and monitor "vehicle speed" item on the scantool.
4. Are those "VSS" parameters displayed correctly?
YES - Fault is intermittent caused by poor contact in 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 "Terminal and Connector Inspection" procedure.
Terminal and 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 "Signal Circuit Inspection" procedure.
Signal Circuit Inspection
CAUTION: This procedure is applied to vehicle with ABS (or ESP). In case of no ABS (or ESP), refer to "C1203 Wheel speed sensor front-RH open/short".
1. Check short to ground in harness
1. IG "OFF"
2. Disconnect PCM connector and ABS or EPS control module connector.
3. Measure resistance between terminal 52 of PCM harness connector and chassis ground.
Specification: Infinite
4. 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.
2. Check for open in harness
1. Ignition "OFF"
2. Disconnect PCM connector and ABS or ESP control module connector.
3. Measure resistance between terminal "52" of PCM harness connector and terminal "14 (With ESP: Terminal 40)" of ABS control module harness connector.
Specification: Approx. below 1 ohm
CAUTION: This picture is only applied to vehicle with ABS
4. Is the measured resistance within specifications?
YES - Go to "Check wheel speed sensor" procedure.
NO
- Check open in harness.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
3. Check wheel speed sensor
1. IG "OFF"
2. Check open or short in wheel speed sensor (Refer to "C1203 Wheel speed sensor front-RH open/short")
3. Is the wheel speed sensor normal?
YES - Substitute with a known - good PCM/ ABS or ESP control unit and check for proper operation. If the problem is corrected, replace PCM/ ABS or ESP control unit and go to "Verification of Vehicle Repair" procedure.
NO
- Repair or replace it as necessary.
- And then go to "Verification of Vehicle Repair" procedure.
CAUTION: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others
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 test 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.