For 1990-2009 cars

### 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 Descriptors

DTC P0500: Vehicle Speed Sensor Circuit Malfunction

### Circuit/System Description

The vehicle speed sensor (VSS) provides vehicle speed information to the power-train engine control module (ECM). The VSS is a permanent magnet generator. The VSS produces an AC voltage as rotor teeth on the output shaft of the transmission pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The ECM converts the pulsing voltage to vehicle speed. The ECM uses the vehicle speed signal to determine shift timing and torque converter clutch (TCC) scheduling. When the ECM detects a low vehicle speed when there is a high engine speed in a drive gear range, then DTC P0502 sets. DTC P0502 is a type B DTC.

### Conditions for Running the DTC

• | No MAP sensor DTCs are set.

• | No TP sensor DTCs are set.

• | The engine vacuum is 0-105 kPa (0-15 psi).

• | The engine torque is 54-542 N·m (40-400 lb ft).

• | The TP angle is greater than 12 percent.

• | The engine speed is greater than 3,000 RPM.

• | The transmission is not in PARK or NEUTRAL.

### Conditions for Setting the DTC

#### P0500

The transmission output speed is less than 150 RPM for 3 seconds.

### Action Taken when the DTC Sets

DTCs P0500 is a type B DTC.

### Conditions for Clearing the MIL/DTC

DTCs P0500 is a type B DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Engine running. Operate the vehicle within the conditions for running the DTC, DTC P0500 should not set.

### Circuit/System Testing

1. Ignition ON, engine OFF.
2. Disconnect the VSS sensor.
3. Connect a DMM between the low reference circuit of the VSS harness connector and a known ground.

⇒ | If the voltage is less than 4.9 volts, test the VSS power circuit for a short to ground or an open/high resistance.

⇒ | If the voltage is greater than 5.2 volts, test the VSS power circuit for a short to voltage.

⇒ | If the VSS circuit tests normal and the voltage is not within the proper range then replace the ECM.

4. Connect a 3 A fusible link wire between the signal circuit of the VSS and the low reference circuit.

⇒ | Using a scan tool, observe the VSS sensor parameters while connecting and disconnecting the link between the VSS sensor signal and the low reference circuit.

⇒ | The VSS should switch between the upper and lower limits.

⇒ | If the VSS signal does not switch between the upper and lower limits then replace the ECM.

⇒ | If the VSS signal does switch between the upper and lower limits then replace the VSS.

### Component Testing

No component tests are available for the VSS sensor.

### Repair Instructions

Important: Always perform the Diagnostic Repair Verification .

Control Module References .

Engine Control Module Replacement .