P0500 – Vehicle speed sensor (VSS) -circuit malfunction

By Mia (Contact Me)
Last Updated 2015-12-05
ASE Master Tech

Table of Contents

1. What Does Code P0500 Mean?
2. What are the common causes of code P0500?
3. What are the symptoms of code P0500?
4. How do you troubleshoot code P0500?
5. Codes Related to P0500
6. Get Help with P0500

What Does Code P0500 Mean?

As you can probably guess, the vehicle speed sensor (VSS) is used to determine vehicle speed. This information is used by various ECUs throughout the vehicle, including the PCM and TCM. The PCM uses the VSS signal to determine the control of outputs such as EGR function and speedometer operation. The TCM uses the VSS signal to control outputs such as upshifts, downshifts and torque convert clutch engagement.

There are three types of vehicle speed sensors: magnetic pickup, Hall Effect and reed switch:

• Reed design: opens and closes a circuit as it’s rotated to produce a digital signal.

A typical reed sensor

(Courtesy: autospeed.com)

• Permanent magnetic: creates an AC voltage signal that is proportional to vehicle speed.

A typical permanent magnet sensor

(Courtesy: auto-tim.blogspot.com)

• Hall Effect: uses a reference voltage from the PCM to produce a DC voltage signal.

A typical Hall Effect sensor

(Courtesy: rowehankins.com)

Most sensors today are of the permanent magnet design or Hall Effect design. They are typically mounted in the transmission or differential assembly. If the PCM detects a problem with the VSS or its circuit, it sets a code and illuminates the check engine light. One such code is P0500, which stands for vehicle speed sensor malfunction.

What are the common causes of code P0500?

To sum things up, the common causes for code P0500 are as follows:

• Failed speed sensor
• Fault in the speed sensor circuit
• Problem with the PCM

What are the symptoms of code P0500?

Symptoms may include shift problems, engine performance problems and improper speedometer function. In some cases, the only symptom will be an illuminated check engine light. Other lights may be on as well, such as ABS and traction control.

How do you troubleshoot code P0500?

The following steps will help you troubleshoot a P0500 code:

• Perform a visual inspection of the sensor and connection.

Many problems can easily be found in the harness and connectors. So, begin your diagnosis by visually inspecting the sensor and its connection.

• Check the VSS with a scan tool

Connect a scan tool under the dash and scroll through the live data until you find the VSS PID. Monitor the VSS while driving and see if it corresponds to how fast you are driving. If the reading doesn’t match your actual speed, something is wrong with the sensor or its circuit. If the reading does match but you still have a P0500 code, you likely have an intermittent problem.

• Test the sensor output

If your vehicle fails the test listed above, it’s time to determine what part of the VSS circuit is to blame. Testing the sensor varies slightly, depending on which type of sensor your vehicle uses.

• Reed switch sensor: To test a reed switch, rotate the speedometer cable or wheel and, with an ohmmeter, see if the circuit opens and closes.

• Permanent magnet sensor: A permanent magnet sensor can be tested using an ohmmeter as well. Remove the sensor connector and attach the meter to the sensor terminals. Most sensors should read between 190 to 250 ohms, but it’s a good idea to consult the manufacture’s repair information for the exact specification. Of course, a meter reading of OL measure there is an open in the sensor and it should be replaced. Next, put the vehicle on a hoist and place it in drive. Rotate the wheels and watch the ohmmeter – the reading should fluctuate. You can also do this with your meter set to read AC voltage. If there is no change in the reading, the sensor is bad and should be replaced.

Testing a permanent magnet sensor

(Courtesy: autozone.com)

• Hall Effect sensor: Using the repair information for your vehicle, determine which pin on the sensor connector is the signal return wire. Using your multimeter on the DC voltage setting, back probe the sensor wire. Attach the black multimeter cable to battery ground. Turning the wheels, you should see the voltage reading on the meter fluctuate.

Testing a Hall Effect sensor

(Courtesy: hubpages.com)

While a meter can be used to test VSS sensors, it’s much better to test them with an oscilloscope. A scope allows you to view the sensor signal waveform pattern and check for any inconsistencies. A magnetic pickup sensor will produce an alternating sine wave pattern. This pattern will go above and below the zero point on the scope. On the other hand, a Hall Effect sensor produces a digital, square waveform pattern. This signal never dips below the zero point.

Permanent magnet waveform pattern examples

(Courtesy: brakeandfrontend.com)

A Hall Effect waveform pattern

(Courtesy: agcoauto.com)

• Check the circuit

If the VSS checks out OK, but you still have P0500 code illuminated, you’ll need to check the sensor circuit.

• Reed switch sensor: A reed switch VSS circuit is pretty simple. The sensor will have two wires going to it: power and the return signal to the PCM. Consult the repair manual for your vehicle to determine which wire is which. Next, connect the red multimeter lead to the power pin on the connector and the black lead to ground. In most cases, you should see around 5 volts. Next, check that there is continuity to the PCM. You can do this by touching one meter lead to the return signal pin on the sensor connector and the other to signal pin on the PCM. Set your meter to the ohms setting – you should see a value appear on the screen. If instead, your meter read OL, you have an open circuit and will need to trace the factory wiring diagram.

• Permanent magnet sensor: A permanent magnet sensor produces its own voltage, so it will only have two wires going to it – ground and return signal. Start by consulting the wiring diagram for your vehicle to determine which pin on the connector is signal and which is ground. Next, connect the red multimeter lead to the battery positive terminal and the black lead to the ground pin. You should see a reading of about 12 volts indicating a good ground. If not, you’ll need to consult the ground side of the wiring diagram to find where the circuit fault lies. Next, check that there is continuity to the PCM. You can do this by touching one meter lead to the return signal pin on the sensor connector and the other to signal pin on the PCM. Set your meter to the ohms setting – you should see a value appear on the screen. If instead, your meter read OL, you have an open circuit and will need to trace the factory wiring diagram.

• Hall Effect Sensor: A Hall Effect Sensor has three wires: signal, reference and ground. Start by consulting the wiring diagram for your vehicle to determine which pin on the connector is which. Next, connect the red multimeter lead to the battery positive terminal and the black lead to the ground pin. You should see a reading of about 12 volts indicating a good ground. Then, check that the 5-volt reference is getting to the sensor by connecting the red multimeter lead to the reference voltage pin and the other to ground. You should see a reading of about 5 volts indicating a good reference voltage. Finally, check that there is continuity to the PCM. You can do this by touching one meter lead to the return signal pin on the sensor connector and the other to signal pin on the PCM. Set your meter to the ohms setting – you should see a value appear on the screen. If instead, your meter read OL, you have an open circuit and will need to trace the factory wiring diagram.

If the sensor and circuit test OK, there is only one item left to blame – the PCM. Before you replace the PCM however, it’s a good idea to double check your testing up to this point. PCMs rarely go bad and they are expensive to replace.

Codes Related to P0500

DTC P0501: Vehicle speed sensor (VSS) range/performance

DTC P0502: Vehicle speed sensor (VSS) ‘A’ low output

DTC P0503: Vehicle speed sensor (VSS) ‘A’ intermittent/erratic/high

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