D16/D20 - Manual Transmission
DTC P0502 or P0503
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 P0502
-
Vehicle Speed Sensor (VSS) Circuit Low Voltage
DTC P0503
-
Vehicle Speed Sensor (VSS) Circuit Intermittent
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The vehicle speed information is provided to the K20 engine control module (ECM) by the vehicle speed sensor (VSS). In the manual transmission service schematics the VSS is also referred to as the transmission output shaft speed sensor. The VSS sensor is a three wire sensor connected to a 5 V reference circuit, a low reference circuit, and a signal circuit to the K20 ECM. The VSS is mounted to the transmission assembly and produces a square wave that increases in frequency as the vehicle speed increases.
Conditions for Running the DTC
P0502
* DTCs P0502 or P0503 are not set.
* The ignition voltage is greater than 9 V.
* Engine speed is greater than 1500 RPM.
P0503
* DTCs P0502 or P0503 are not set.
* The ignition voltage is greater than 9 V.
* VSS signal is greater than 200 RPM for 2 seconds.
* VSS signal change is less than 150 RPM for 2 seconds.
Conditions for Setting the DTC
P0502
The VSS signal is less than 60 RPM for 5 seconds.
P0503
The VSS signal change is greater than 350 RPM within a calibrated time range.
Action Taken When the DTC Sets
DTC P0502 or P0503 are Type B DTCs.
Conditions for Clearing the DTC
DTC P0502 or P0503 are Type B DTCs.
Reference Information
Schematic Reference
Manual Transmission Schematics D16/D20 - Manual Transmission
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
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 (LUW) Scan Tool Testing and ProceduresEngine Control Module Scan Tool Information (LUV)
Circuit/System Verification
1. If any other DTCs are set, diagnose them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. With a scan tool, road test the vehicle. Verify that the vehicle speed sensor parameter increases in value, displays the same value as the instrument panel speed indicator and does not spike upward or drops out completely.
• If the VSS signal does not perform as indicated
Refer to Circuit/System Testing below.
• If the VSS signal does perform as indicated
3. 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 harness connector of the B14A VSS electrical harness connector.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal A and ground on the engine or transmission assembly.
• If greater than the specified value
Test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
• If less than the specified value
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal C and ground on the engine or transmission assembly.
• If not within the specified range
Test the 5 V reference circuit for a short to B+, short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If within the specified range
4. Ignition OFF, install an jumper wire between the low reference circuit terminal A on the B14A transmission output shaft speed sensor and terminal A on the speed sensor harness connector.
5. Ignition ON, monitor the VSS signal parameter with a scan tool, when performing the next step.
6. Momentary install a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal C. Perform this action several times. Verify that the VSS signal parameter indicates vehicle speed.
• If vehicle speed is not indicated
Test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If vehicle speed is indicated
7. If all circuits test normal, replace the B14A VSS.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Vehicle Speed Sensor Replacement Service and Repair
* Control Module References Control Module References
* Engine Control Module Programming and Setup (LUW) Testing and Inspection