GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 Transmission/Transaxle 🢒 Manual Transmission - NV 3500 🢒 DTC P0500

Object Number: 662622 Size: LF
OBD II Symbol Description Notice

Circuit Description

Vehicle speed information is provided to the powertrain control module (PCM) by the vehicle speed sensor (VSS). The VSS is a permanent magnet generator that is mounted on the transfer case and produces a pulsing voltage when vehicle speed is over 5 km/h (3 mph). The AC voltage amplitude and frequency increases with vehicle speed. The PCM converts the pulsing voltage into km/h (mph). The PCM supplies the necessary signal to the instrument panel for speedometer, odometer operation and to the cruise control module.

If the PCM detects no vehicle speed for a specified length of time while other sensors indicate that the vehicle is moving, DTC P0500 sets. DTC P0500 is a type B DTC.

Conditions for Running the DTC
    • No Manifold Absolute Pressure (MAP) Sensor DTCs P0106, P0107 or P0108.
    • No throttle position (TP) or accelerator pedal position (APP) sensor DTCs P0121, P0122, P0123, P1120, P1125, P1220, P1221, P1514, P1515, P1516, P1517, or P1518.
    • No crankshaft position sensor DTCs P0335 or P0336.
    • The ECT is greater than 35°C (95°F).
    • The TP sensor angle is 5-100 percent.
    • The engine speed is greater than 1,000 RPM.
    • The MAP is 40-100 kPa (6-15 psi).
    • All of the above conditions are met for 2 seconds.

Conditions for Setting the DTC

The PCM detects no vehicle speed for 50 seconds.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.
    • The PCM disables Cruise Control.
    • The PCM records the operating conditions at the time when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
    • The PCM stores P0500 in PCM history.

Conditions for Clearing the MIL/DTC
    • The PCM turns OFF the MIL after three consecutive ignition cycles in which the diagnostic test runs and passes.
    • The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.
    • The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
    • A scan tool can clear the MIL/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. This step ensures that the technician performed a Diagnostic System Check - Manual Transmission.

  2. This step tests to see if the PCM is receiving a signal from the VSS, using the scan tool.

    3.

  3. This step tests the entire VSS system for proper output voltage.

  4. This step tests the VSS High Signal and VSS Low Signal circuits for opens, shorts and high resistance.

    5.

  5. This step ensures the technician inspects the VSS related mechanical components and mounting.

    6.

  6. This step verifies if the PCM has taken required action after setting DTC P0502.

  7. This step tests the VSS High Signal and VSS Low Signal circuits for total circuit resistance. 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.

  8. This step replaces the PCM. 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 and to CKP System Variation Learn Procedure in Engine Controls.

  9. This step validates that the repair has fixed the DTC under normal operating conditions.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Manual Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Manual Transmission

2

  1. Raise the vehicle and support the rear axle with jack stands.
  2. Start the vehicle.
  3. Engage the transmission in second gear.
  4. Observe the VSS data on the scan tool data list.

Is the vehicle speed greater than the specified value?

0 km/h (0 mph)

Go to Step 6

Go to Step 3

3

  1. Turn the ignition switch OFF.
  2. Remove the VSS High Signal and VSS Low Signal circuit wires from the PCM connector.
  3. Connect the PCM connector to the PCM.
  4. Start the vehicle.
  5. Engage the transmission in second gear.
  6. With a DMM, measure AC voltage at the two VSS wires.

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

0.5 V AC

Go to Step 7

Go to Step 4

4

  1. Turn the ignition switch OFF.
  2. Put the transmission in NEUTRAL.
  3. Install the VSS High and VSS Low circuit wires at the PCM.
  4. Disconnect the VSS and the PCM connectors.
  5. Test both the VSS High and VSS Low circuits for high resistance, opens, shorts to ground and shorts to each other.

Did you find any of the above conditions?

--

Go to Step 8

Go to Step 5

5

  1. Connect the PCM connector.
  2. Remove the VSS, but do not replace it at this time. Refer to Vehicle Speed Sensor .
  3. Inspect the VSS and the VSS rotor for the following conditions:
    4. • VSS damage
    • VSS rotor damage

Did you find any damage?

--

Go to Step 9

Go to Step 10

6

Is the speedometer operating normally?

--

Go to Step 12

Go to Step 3

7

  1. Turn the ignition switch OFF.
  2. With a DMM, measure the total circuit resistance through both VSS circuits, including the VSS sensor.

Is the total resistance within the specified value?

966-2,200 ohms

Go to Step 11

Go to Step 4

8

Repair the affected VSS High signal or VSS Low signal circuit, as necessary.

Did you complete the repair?

--

Go to Step 12

--

9

Replace the VSS rotor or make any necessary repairs to the VSS mount.

Did you complete the repairs?

--

Go to Step 12

--

10

Replace the VSS. Refer to Vehicle Speed Sensor .

Did you complete the repairs?

--

Go to Step 12

--

11

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.3L.

Did you complete the repairs?

--

Go to Step 12

--

12

  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Test drive the vehicle.
  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