GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 GTO 🢒 DTC 🢒 DTC P0500

Circuit Description

A toothed wheel mounted on the output shaft of the transmission generates an AC voltage pulse as it moves past the vehicle speed sensor (VSS). The VSS contains a permanent magnet surrounded by a coil of wire, which produces a magnetic field. The toothed wheel interrupts the magnetic field that generates an AC voltage pulse. As the vehicle speed increases the AC voltage pulse rate also increases.

Conditions for Running the DTC
    • DTCs P0107, P0108, P0117, P0118, P0121, P0122 or P0123 are not set.
    • The engine coolant temperature (ECT) is more than 35°C (95°F).
    • No idle control system DTCs P0506 or P0507 are not set.
    • The engine speed is more than 1,000 RPM.
    • The throttle position (TP) sensor angle is 5-100 percent.
    • The manifold absolute pressure (MAP) is between 40-100 kPa (6-15 psi) when the A/C is OFF.
    • The MAP is between 45-100 kPa (7-15 psi) when the A/C is ON.
    • All conditions are met for 2 seconds.

Conditions for Setting the DTC

The powertrain control module (PCM) detects vehicle speed at 0 km/h (0 mph) for 100 seconds.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

Ensure the VSS is correctly torqued to the transmission housing.

Test Description

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

  1. The resistance measurement will not change if either the VSS high signal circuit or the VSS low signal circuit, but not both, is shorted to ground. The vehicle speed detector in the PCM and the VSS are matched in such a way that an open or a short to ground in the VSS low signal circuit will not usually cause a loss of speed signal or a DTC P0500 to set. The lower resistance value given represents the nominal resistance specification of the VSS at -40°C (-40°F), minus the manufacturing tolerance specification of 10 percent. The higher resistance value given represents the nominal resistance specification of the VSS at 150°C (302°F), plus the manufacturing tolerance specification of 10 percent.

    2.

  2. This step isolates the short between the VSS and the wiring.

    3.

  3. The DMM will detect AC voltage if the VSS high signal circuit is shorted to ground.

    4.

  4. The replacement PCM must be programmed and the crankshaft position system variation procedure must be performed. Refer to the latest Techline procedures for PCM reprogramming.

Step

Action

Value(s)

Yes

No

Schematic Reference: Manual Transmission Schematics

1

Did you perform the Diagnostic System Check - Manual Transmission?

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Go to Step 2

Go to Diagnostic System Check - Manual Transmission

2

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

  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.

    3. Important: Record the Failure Records before clearing the DTCs. Using the Clear Info function erases the Failure Records from the powertrain control module (PCM).

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Raise the drive wheels.
  6. Support the lower control arms so that the drive axles are in a horizontal, straight, position.
  7. Start the engine.
  8. Disable the antilock brake system (ABS)/traction control system (TCS) System, if equipped.
  9. Allow the engine to idle in gear.

Does the scan tool display vehicle speed above the specified value?

0 km/h (0 mph)

Go to Step 3

Go to Step 4

3
  1. Turn OFF the ignition.
  2. Turn ON the ignition with the engine OFF.
  3. Review the Freeze Frame data and note the parameters.
  4. Start the engine.
  5. Operate the vehicle within the Freeze Frame conditions and Conditions for Running the DTC as noted.

Does the scan tool display vehicle speed above the specified value?

0 km/h (0 mph)

Go to Diagnostic Starting Point - Engine Controls

Go to Step 4

4
  1. Verify that the latest calibration is installed in the PCM.
  2. Update the PCM with the latest calibration as necessary.

Did the PCM require a calibration update?

--

Go to Step 14

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Measure the resistance between terminal C2 20 and C2 21.

Is the resistance within the specified range?

1668-2913 ohms

Go to Step 7

Go to Step 6

6

Test the vehicle speed sensor (VSS) high signal and VSS low signal circuits for the following conditions:

    • An open circuit or high resistance condition
    • VSS high signal and VSS low signal circuits shorted together

Refer to Testing for Intermittent Conditions and Poor Connections .

Did you find and correct a condition?

--

Go to Step 14

Go to Step 11

7

Measure the resistance between the terminal C2 21 and ground.

Is the resistance greater than the specified value?

50 K ohms

Go to Step 10

Go to Step 8

8

  1. Leave the DMM connected between terminal C1 64 and ground.
  2. Disconnect the VSS.
  3. Measure the resistance between terminal C2 21 and ground.

Is the resistance greater than the specified value?

50 K ohms

Go to Step 11

Go to Step 9

9

Repair the short to ground in the VSS high signal circuit.

Did you complete the repair?

--

Go to Step 14

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10

  1. Connect the DMM between the terminals C2 20 and C2 21.
  2. Measure the AC voltage with the DMM while rotating the drive wheels by hand.

Is the AC voltage equal to or greater than the specified value?

0.5 V

Go to Step 14

Go to Step 11

11
  1. Remove the VSS. Refer to Vehicle Speed Sensor Replacement .
  2. Inspect the VSS and the VSS rotor for the following conditions:
    3. • VSS damage
    • VSS rotor damage
    • Excessive air gap between the VSS rotor and the VSS
    • Incorrect alignment between the VSS and the VSS rotor
  3. Repair or replace any of the above items as necessary.

Did you find and correct a condition?

--

Go to Step 14

Go to Step 12

12

Replace the VSS.

Did you complete the repair?

--

Go to Step 14

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13

Replace the PCM. Refer to Engine Control Module Replacement .

Is the action complete?

--

Go to Step 14

--

14
  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Idle at normal operating temperature.
  4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the scan tool indicate that this diagnostic has run and passed?

--

System OK

Go to Step 2