P0501
DTC P0501 or P0502
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.
DTC Descriptors
DTC P0501
- Vehicle Speed Sensor (VSS) Performance
DTC P0502
- Vehicle Speed Sensor (VSS) Circuit Low Voltage
Diagnostic Fault Information
Typical Scan Tool Information
Circuit/System Description
Vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The VSS consists of a hall-effect sensor mounted to the transmission case which interfaces with a rotor pressed onto the transmission output shaft. The hall-effect sensor contains a permanent magnet and a semiconductor plate to which ignition voltage is applied. As the output shaft spins, the rotor directs the field of the permanent magnet either toward or away from the plate. The VSS produces a frequency signal that is proportional to vehicle speed. The ECM converts the VSS signal to vehicle speed, displayed on the scan tool in kilometers per hour or miles per hour. The ECM also uses the VSS signal to generate the 4,000 pulses per mile vehicle speed signal used by the instrument cluster.
Conditions for Running the DTC
* The engine speed is greater than 1800 RPM for 3 seconds.
* The engine coolant temperature (ECT) is greater than 40°C (104°F).
Conditions for Setting the DTC
The VSS indicates a speed of less than 0 km/h (0 mph) for 4 seconds.
Action Taken When the DTC Sets
* P0501 and P0502 are Type B DTCs.
* The ECM disables cruise control.
Conditions for Clearing the MIL/DTC
P0501 and P0502 are Type B DTCs.
Diagnostic Aids
The battery must be fully charged and pass a battery test. Refer to Battery Inspection/Test (Battery Inspection/Test).
Reference Information
Schematic Reference
Manual Transmission Schematics (Aisin AY6 - Manual Transmission)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Transmission System Description and Operation (Aisin AY6 - Manual Transmission)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Engine Control Module Scan Tool Information (LS3, L99) (Scan Tool Testing and Procedures)Engine Control Module Scan Tool Information (LLT) (Scan Tool Testing and Procedures)
Circuit/System Verification
1. Operate the vehicle on the road at 64 km/h (40 mph). Observe the transmission vehicle speed sensor parameter with a scan tool. The VSS signal should match the instrument panel speedometer indicator.
2. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections).
Circuit/System Testing
Note: You must perform the Circuit/System Verification first.
1. Ignition OFF, disconnect the X2 harness connector at the ECM.
2. Disconnect the VSS harness connector.
3. Ignition OFF, test for less than 5 ohm between the ground circuit at the VSS harness connector terminal 3 and ground.
• If greater than the specified value, repair the open/high resistance condition.
4. Ignition ON, test for less than 1 V between the signal circuit terminal 1 and ground at the VSS harness connector.
• If greater than the specified value, test the signal circuit for a short to voltage.
5. Ignition ON, test for greater than 11 V between the ignition voltage circuit, at the VSS harness connector terminal 3, and ground.
• If less than the specified value, test the ignition voltage circuit for a short to ground or an open/high resistance.
6. Ignition ON, install a 3 A fused jumper wire between the ignition voltage circuit terminal 3 and the signal circuit terminal 1 at the VSS harness connector. Test for greater than 11 V at X2, terminal 43 of the ECM harness connector.
• If less than the specified value, test the VSS signal circuit for a short to ground, or an open/high resistance.
7. Remove the 3 A fused jumper wire.
8. Ignition ON, engine OFF, transmission in NEUTRAL.
9. Install a 3 A fused jumper wire between the ignition voltage circuit terminal 1 on the VSS harness connector and terminal 1 on the VSS. Connect a second jumper wire between the ground circuit terminal 2 on the VSS harness connector and terminal 2 on the VSS.
10. Test for greater than 0.15 V AC, at terminal 1 on the VSS sensor, while rotating the rear wheels by hand.
• If less than the specified value, replace the VSS.
11. If all circuits test normal, replace the ECM.
Component Testing
Note: You must perform the Circuit/System Verification first.
1. Remove the VSS sensor. Refer to Vehicle Speed Sensor Replacement (Aisin AY6 - Manual Transmission).
2. Inspect and repair the VSS or the transmission for the following conditions:
* Loose or damaged VSS
* Excessive VSS to rotor gap
* Incorrect VSS rotor alignment
* Loose or damaged VSS rotor
• Repair or replace as necessary.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Vehicle Speed Sensor Replacement (Aisin AY6 - Manual Transmission)
* Engine Control Module Programming and Setup (LS3, L99) (Testing and Inspection)Engine Control Module Programming and Setup (LLT) (Testing and Inspection)
* Engine Control Module Replacement (Service and Repair)