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Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 4:  The vehicle speed detector in the ECM 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.
  2. 8:  This step isolates the short between the VSS and the wiring.
DTC P0500 (6.6L)

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls - 6.6L
2
    NOTE: 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 ECM.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Raise the drive wheels.
  6. Start the engine.
  7. 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.
Does the scan tool display vehicle speed above the specified value?		 0 km/h (0 mph) Go to Intermittent Conditions in Engine Controls - 6.6L Go to Step 4 
4 
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Measure the resistance between the VSS low signal and the VSS high signal circuits.
Is the resistance within the specified range?		 1,680-3,160 Ω Go to Step 6  Go to Step 5 
5 Test the VSS high signal circuit and the VSS low signal circuit for the following conditions:
  • An open circuit or high resistance condition
  • VSS high signal circuit and VSS low signal circuit shorted together

Refer to Circuit Testing in Wiring Systems.
Did you find and correct a condition?		 - Go to Step 14  Go to Step 11 
6 Measure the resistance between the VSS high signal circuit and ground.
Is the resistance greater than the specified value?		 10 M Ω Go to Step 7  Go to Step 8 
7
  1. Disconnect the engine wiring harness from the VSS assembly.
  2. Turn ON the ignition, with the engine OFF.
  3. Test the VSS high signal circuit of the VSS assembly for a short to voltage.

    Refer to Testing for a Short to Voltage andWiring Repairs in Wiring Systems.

Did you find and correct the condition?		 - Go to Step 14  Go to Step 10 
8 
  1. Leave the DMM connected between the VSS high signal circuit and ground.
  2. Disconnect the VSS.
  3. Measure the resistance between the VSS high signal circuit and ground.
Is the resistance greater than the specified value?		 10 M Ω Go to Step 12  Go to Step 9 
9 Repair the short to ground in the VSS high signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 14  -
10
  1. Connect the ECM connector C2.
  2. Connect the DMM between the VSS low signal and the VSS high signal circuits.
  3. 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 13  Go to Step 11 
11
  1. Remove the VSS. Refer to Vehicle Speed Sensor (VSS) Replacement .
  2. Inspect the VSS and the VSS rotor for the following conditions:
    • 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. Refer to Vehicle Speed Sensor (VSS) Replacement .
Did you complete the repair?		 - Go to Step 14  -
13 Replace the ECM. Refer to Engine Control Module (ECM) Replacement in Engine Controls - 6.6L.
Is the action complete?		 - Go to Step 14  -
14 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle in order to achieve a vehicle speed of greater than 3 km/h (2 mph) for 2 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0500.

Has the test run and passed?		 - Go to Step 15  Go to Step 2 
15 With the scan tool, observe the stored information, capture info and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 6.6L System OK
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