GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Prizm 🢒 Engine 🢒 Engine Controls - 1.8L 🢒 DTC P0500

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 through 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 speedometers 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 the vehicle speed.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC
    • No vehicle speed sensor signal is sent to the PCM.
    • The engine speed is between 2,000 and 5,000 RPM.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 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.

Conditions for Clearing the MIL/DTC
    • The MIL turns OFF after 3 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 of more than 5 km/h (3 mph). DTC P0500 can be falsely set if the engine is brake-torqued in gear. Disregard 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 the components for any of the following conditions:

    • Any backed-out terminals
    • Any improper mating of terminals
    • Any broken electrical connector locks
    • Any improperly formed or damaged terminals
    • Any faulty terminal-to-wire connections
    • Any physical damage to the wiring harness
    • A broken wire inside the insulation
    • Any corrosion of the electrical connections, the splices, or the 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 approximately equal to one mile per hour.

Step

Action

Values

Yes

No

Schematic Reference:

VSS Output


Object Number: 624339 Size: FS
HO2S
Engine Controls Components
EVAP Controls, and IAC Valve
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
 .

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 - Automatic Transmission

2
  1. Raise the drive wheels.
  2. Support the lower control arms so that the drive axles are in a horizontal 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 a 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 DTC P0500 set?

--

Go to Step 4

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 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 a 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 Diagnostic Starting Point - Instrument Panel, Gages and Console

6

  1. Turn OFF the ignition.
  2. Disconnect the VSS electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the VSS connector terminal 1 on the 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 on the harness side with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 13

8

Probe the VSS connector terminal 3 on the harness side with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 9

9

  1. Reconnect the VSS connector.
  2. Disconnect the instrument panel cluster (IPC) connector C2.
  3. Set-up the digital multimeter (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, with the engine OFF.
  4. Probe the vehicle speed input circuit terminal on the harness side with the DMM connected to ground.
  5. Measure the DC voltage on the vehicle speed input circuit.

Is the voltage within the specified value?

9-12 V

Go to Step 11

Go to Step 16

11

  1. Set-up the 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 Speedometer Replacement in Instrument Panel, Gauges, and Console.

Is the replacement complete?

--

Go to Step 21

--

19

Replace the VSS. Refer to Speedometer Replacement in Instrument Panel, Gauges, and Console.

Is the replacement complete?

--

Go to Step 21

--

20

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 1.8 L.

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 Diagnostic Trouble Code (DTC) List/Type

System OK