GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Prizm 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 DTC P0500 Vehicle Speed Sensor (VSS) Circuit

Refer to

Cell 20: VSS Output


Object Number: 245752 Size: FS
Cell 20: HO2S
Engine Controls Components
Cell 20: EVAP Controls, IAC, PSP Switch
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Cell 10: Gauge Fuse
Cell 10: Gauge Fuse
Cell 10: Gauge Fuse
Cell 34: Vehicle Speed Sensor
Cell 81: Gages, Speedometer, and Low Fuel Indicator
Cell 81: Gages, Speedometer, and Low Fuel Indicator
Cell 14: G201 and G202
 schematic.

Circuit Description

The vehicle speed sensor (VSS) is mounted on the transaxle. As the transaxle turns the VSS, the VSS provides the speedometer with a vehicle speed input (voltage pulses). Each revolution of the axleshaft equals 4 pulses. This input is used to drive the speedometer.

The speedometer converts the vehicle speed input to a more precise output which is sent to the powertrain control module (PCM) and the cruise control module (if equipped). The PCM sends a 5 volt carrier signal to the speedometer's vehicle speed output control circuit. On this same circuit, the speedometer produces a pulse width modulated signal that the PCM (and the cruise control module) use to determine vehicle speed.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

Manual Transaxle vehicle:

    • No vehicle speed sensor signal to PCM.
    • Engine speed is between 2,000 and 5,000 RPM.

Automatic Transaxle vehicle:

    • No vehicle speed sensor signal to PCM.
    • Park/Neutral position switch is OFF.
    • Engine speed is equal to or greater than 2,350 RPM.
    • TP angle is equal to or greater than 13 degrees.
    • Engine parameters indicate the vehicle is being driven.

Action Taken When the DTC Sets

Manual Transaxle and 3 speed A/T vehicle:

    • The PCM illuminates the malfunction indicator lamp (MIL) after two consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

4 speed Automatic Transaxle vehicle:

    • The PCM illuminates the malfunction indicator lamp (MIL) the FIRST time the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC
    • The MIL turns OFF after three consecutively passing trips without a fault present.
    • A History DTC clears after 40 consecutive warm-up cycles without a fault.
    • Use the scan tool Clear DTC Information function.

Diagnostic Aids

A scan tool should indicate a vehicle speed whenever the drive wheels are turning at a speed greater than 5 km/h (3 MPH). DTC P0500 can be falsely set if the engine is brake-torqued in gear. Disregard a DTC P0500 if the DTC sets when the drive wheels are not turning.

An intermittent malfunction may be caused by a fault in the VSS sensor electrical circuit. Inspect the wiring harness and components for any of the following conditions:

    • Backed out terminals.
    • Improper mating of terminals.
    • Broken electrical connector locks.
    • Improperly formed or damaged terminals.
    • Faulty terminal to wire connections.
    • Physical damage to the wiring harness.
    • A broken wire inside the insulation.
    • Corrosion of electrical connections, splices, or terminals.

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.

The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

Test Description

The numbers below refer to the step numbers in the diagnostic table.

  1. This step checks the VSS sensor for a battery positive supply.

    2.

  2. This step checks the VSS sensor for a ground supply.

    3.

  3. This step checks for a shorted to ground speedometer vehicle speed input circuit.

    4.

  4. This step checks the VSS for an output signal.

    5.

  5. This step checks the PCM vehicle speed input circuit for continuity to the speedometer.

    6.

  6. This step checks the speedometer for an output signal. Each 1 Hz of frequency is aproximately equal to one mile per hour.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Raise the drive wheels.
  2. Support the lower control arms so that the drive axles are in a horizontal (straight) position.
  3. Start and idle the engine.
  4. Observe the vehicle speed parameter on the scan tool.
  5. Allow the engine to idle in gear with the drive wheels rotating.

Does the scan tool parameter indicate vehicle speed?

--

Go to Step 3

Go to Step 4

3
  1. Using the scan tool store the DTC Freeze Frame information.
  2. Perform the scan tool Clear DTC Information function.
  3. Place the vehicle into Check Mode using the scan tool.
  4. Operate the vehicle within the Freeze Frame conditions.

Does a DTC P0500 set?

--

Go to Step 4

Fault Not Present-Go to Diagnostic Aids

4
  1. Raise the drive wheels.
  2. Support the lower control arms so that the drive axles are in a horizontal (straight) position.
  3. Start and idle the engine.
  4. Observe the speedometer
  5. Allow the engine to idle in gear with the drive wheels rotating.

Does the speedometer indicate vehicle speed?

--

Go to Step 10

Go to Step 5

5

Do all other Instrument Cluster Assembly functions operate normally?

--

Go to Step 6

Go to Instrument Cluster System Check in Body and Accesories

6

  1. Turn the ignition switch OFF.
  2. Disconnect the Vehicle Speed Sensor (VSS) electrical connector.
  3. Turn the ignition switch ON leaving the engine OFF.
  4. Probe the VSS connector terminal 1 (harness side) with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 12

7

Probe the VSS connector terminal 2 (harness side) with a test lamp connected to BATTERY POSITIVE.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 13

8

Probe the VSS connector terminal 3 (harness side) with a test lamp connected to BATTERY POSITIVE.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 9

9

  1. Reconnect the VSS connector.
  2. Disconnect the ICA connector C2.
  3. Set-up the J 39200 DMM to measure the DC frequency (push the Hz button) on the speedometer Vehicle Speed Input circuit (terminal 10).
  4. Start and idle the engine.
  5. Allow the engine to idle in gear with the drive wheels rotating.

Does the DMM indicate a frequency?

--

Go to Step 18

Go to Step 15

10

  1. Turn OFF the ignition.
  2. Disconnect PCM electrical connector C3, containing the Vehicle Speed Input terminal.
  3. Turn ON the ignition, leaving the engine OFF.
  4. Probe the Vehicle Speed Input circuit terminal (harness side) with the J 39200 DMM connected to ground.
  5. Measure the DC voltage on the vehicle speed input circuit.

Is the voltage withn the specified value?

9-12 volts

Go to Step 11

Go to Step 16

11

  1. Set-up the J 39200 DMM to measure the DC frequency (push the Hz button) on the PCM vehicle speed input circuit.
  2. Start and idle the engine.
  3. Allow the engine to idle in gear with the drive wheels rotating.

Does the DMM indicate a frequency?

--

Go to Step 20

Go to Step 17

12

Repair the cause of no power to the VSS connector. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 21

--

13

Repair the cause of no ground to the VSS connector. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 21

--

14
  1. Check the speedometer Vehicle Speed Input circuit for a short to ground.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 21

Go to Step 18

15
  1. Check the speedometer Vehicle Speed Input circuit for an open.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 21

Go to Step 19

16
  1. Check the PCM Vehicle Speed Input circuit for a short to ground or open.

    2. If equipped ensure that the cruise control module is not shorted internally.

  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 21

Go to Step 18

17
  1. Check the PCM Vehicle Speed Input circuit for a short to battery positive.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 21

Go to Step 18

18

Replace the speedometer. Refer to Instrument Cluster Replacement in Body and Accessories.

Is the replacement complete?

--

Go to Step 21

--

19

Replace the VSS. Refer to Vehicle Speed Sensor Replacement .

Is the replacement complete?

--

Go to Step 21

--

20

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the replacement complete?

--

Go to Step 21

--

21
  1. Perform the scan tool Clear DTC Information function and road test the vehicle with the Freeze Frame conditions that set the DTC.
  2. Review the scan tool data and check for DTCs. The repair is complete if no DTCs are stored.

Are any DTCs displayed on the scan tool?

--

Go to the applicable DTC table

System OK