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DTC P0501 or P0502 - FX3

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0502: Vehicle Speed Sensor Circuit Low Voltage

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 magneto-resistive (MR) sensor mounted to the transmission case which interfaces with a rotor pressed onto the transmission output shaft. The MR 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 kilometres per hour or miles per hour. The VSS also sends signal to some modules such as instrument panel cluster (IPC), radio, HVAC control module, or telematics communication interface control module if equipped.

Conditions for Running the DTC

P0502 (Test 1 Power Test)

    • DTC P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0351, P0352, P0353, P0354, or P2110 is not set.
    • The engine is running.
    • The ignition voltage is between 11-16V.
    • The engine coolant temperature is greater than 60°C (140°F).
    • The MAP is greater than 60 kPa (8.7 psi).
    • The throttle position is between 25-60%.
    • The engine speed is between 2000-4000 RPM.
    • The DTC runs continuously when the above conditions are met.

P0502 (Test 2 Deceleration Test)

    • DTC P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0351, P0352, P0353, P0354, or P2110 is not set.
    • The engine is running.
    • The ignition voltage is between 11-16V.
    • The engine coolant temperature is greater than 60°C (140°F).
    • The MAP is greater than 30 kPa (4.4 psi).
    • The throttle position is less than 0.8%.
    • The engine speed is between 1800-6000 RPM.
    • The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the vehicle speed is less than 5 km/h (3.1 mph).

Action Taken When the DTC Sets

DTC P0502 is a Type E DTC.

Conditions for Clearing the DTC

DTC P0502 is a Type E DTC.

Reference Information

Schematic Reference

Manual Transmission Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Transmission System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Operate the vehicle at 16-32 km/h (10-20 mph) while observing the scan tool VSS parameter. The reading should vary with the vehicle speed and match the instrument panel speedometer indicator.
  2. Operate the vehicle within the Conditions for Running the DTC, to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the B115 vehicle speed sensor (VSS).
  2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.
    3. ⇒If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
  3. Ignition ON, verify the test lamp illuminates between the ignition circuit terminal C and the ground circuit terminal A.
    4. ⇒If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

    Note: You may need to disconnect all the modules that share the signal circuit in order to isolate the condition. Refer to Manual Transmission Schematics to identify the modules that share the signal circuit.

  4. Ignition OFF, test for greater than 10Ω between the signal circuit terminal B and ground.
    5. ⇒If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
  5. Ignition OFF, disconnect the harness connector at the K20 ECM.
  6. Ignition OFF, test for less than 5Ω between the signal circuit terminal B on the B115 VSS harness connector and terminal 51 on the K20 ECM harness connector.
    7. ⇒If greater than the specified range, test the signal circuit for an open/high resistance.
  7. Ignition ON, test for less than 10V between the signal circuit terminal B on the B115 VSS harness connector and ground.
    8. ⇒If greater than the specified value, test the signal circuit for a short to voltage.
  8. If all circuits test normal replace the B115 VSS.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for ECM replacement, setup and programming

   


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