The vehicle speed sensor (VSS) assembly provides vehicle speed information to the powertrain control module (PCM). The VSS assembly is a permanent magnet generator. The VSS produces alternating current (AC) as the rotor teeth on the output shaft of the transmission, 2WD, or transfer case, 4WD, pass through the magnetic field of the sensor. The frequency and amplitude of the AC waveform increase as vehicle speed increases.
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.
• | No MAP DTCs P0106, P0107 or P0108. |
• | No ECT DTCs P0117 or P0118. |
• | No idle system DTCs P0506 or P0507. |
• | No TP sensor DTCs P2120, P2121, P2125 or P2135. |
• | The ECT is 35°C (95°F) or greater. |
• | The TP sensor angle is 5-100 percent. |
• | The engine speed is greater than 1,000 RPM. |
• | The MAP is 40-100 kPa with A/C off. |
• | The MAP is 45-100 kPa with A/C on. |
• | All the above conditions are met for more than 2 seconds. |
The PCM detects no vehicle speed for 50 seconds.
• | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails. |
• | Cruise Control is disabled. |
• | 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. |
• | 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. |
Ensure the VSS is correctly torqued to the transmission housing.
The numbers below refer to the step numbers on the diagnostic table.
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.
This step isolates the short between the VSS and the wiring.
The DMM will detect AC voltage if the VSS high signal circuit is shorted to ground.
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 - 4.8L, 5.3L, and 6.0L | ||||||||
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. Important: Record the Failure Records before clearing the DTCs. Using the Clear Info function erases the Failure Records from the PCM. 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 |
Does the scan tool display vehicle speed above the specified value? | 0 km/h (0 mph) | Go to Intermittent Conditions in Engine Controls - 4.8L, 5.3L, and 6.0L | Go to Step 4 | ||||||||
4 |
Is the resistance within the specified range? | 966-2,200 ohms | Go to Step 6 | Go to Step 5 | ||||||||
Test the VSS high signal circuit and the VSS low signal circuit for the following conditions:
Refer to Circuit Testing in Wiring Systems. Did you find and correct a condition? | -- | Go to Step 13 | Go to Step 10 | |||||||||
6 | Measure the resistance between terminal C2 21 and ground. Is the resistance greater than the specified value? | 50 K ohms | Go to Step 9 | Go to Step 7 | ||||||||
7 |
Is the resistance greater than the specified value? | 50 K ohms | Go to Step 10 | Go to Step 8 | ||||||||
Repair the short to ground in the VSS high signal circuit. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- | |||||||||
9 |
Is the AC voltage equal to or greater than the specified value? | 0.5 V | Go to Step 12 | Go to Step 10 | ||||||||
Did you find and correct a condition? | -- | Go to Step 13 | Go to Step 11 | |||||||||
11 | Replace the VSS. Refer to Vehicle Speed Sensor Replacement . Did you complete the repair? | -- | Go to Step 13 | -- | ||||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L. Is the action complete? | -- | Go to Step 13 | -- | ||||||||
13 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 14 | Go to Step 2 | ||||||||
14 | 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 - 4.8L, 5.3L, and 6.0L | System OK |