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 provide an overview of each diagnostic category.

### DTC Descriptor

DTC P0501: Vehicle Speed Sensor (VSS) Circuit

### Circuit/System Description

The vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The VSS is a permanent magnet generator that is mounted to the transmission and produces a pulsing voltage. The AC voltage amplitude and frequency increases with vehicle speed. The ECM converts the pulsing voltage into km/h (mph).

### Conditions for Running the DTC

• | The engine speed is more than 3,488 RPM.

• | The air flow into the engine is greater than a predetermined amount.

• | DTC P0501 runs continuously once 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) for more than 10 seconds.

### Action Taken When the DTC Sets

DTC P0501 is a Type B DTC.

### Conditions for Clearing the DTC

DTC P0501 is a Type B DTC.

### Diagnostic Aids

• | Ensure the VSS is correctly torqued to the transmission housing.

• | This DTC may be set due to an instrument panel (I/P) cluster condition.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Raise the drive wheels.

Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

2. Support the lower control arms so that the drive axles are in a horizontal position.
3. Engine idling. Engage the transmission into 2nd gear.
4. Observe the VSS data parameter with a scan tool. The following should display a vehicle speed once the drive wheels are at a speed above 5 km/h (3 mph):

• | The VSS data parameter

• | The speedometer

5. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the VSS.
2. Connect a test lamp between the ignition 1 voltage circuit of the VSS and ground .
3. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and battery ground.

⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

4. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit and ground.

⇒ | If greater than 5.0 ohms repair the ground circuit for an open/high resistance.

5. Ignition ON, test for 9-11 volts between the signal circuit of the VSS and ground.

⇒ | If less than 9 volts test the VSS signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒ | If greater than 11 volts test the VSS signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

6. If the voltage is within the specified range replace the VSS.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Instrument Cluster Replacement .

• | Control Module References for ECM replacement, setup, and programming