Circuit Description
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 an AC voltage as the rotor teeth on the output shaft of the transmission (2WD) or transfer case (4WD) pass through the sensor's magnetic field. The AC voltage frequency and amplitude increase as the vehicle speed increases.
If the PCM detects no vehicle speed during 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 group 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 1000 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 when the Conditions for Setting the DTC are met. The PCM records this information as Freeze Frame and Failure Records. |
| • | The PCM stores DTC 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 ignition switch is OFF long enough in order to power down the PCM. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission-related diagnostic. |
| • | A scan tool can clear the MIL/DTC. |
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform A Diagnostic System Check - Engine Controls? | -- | ||||||||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records from the PCM. Caution: To avoid any vehicle damage, serious personal injury or death when major components are removed from the vehicle and the vehicle is supported by a hoist, support the vehicle with jack stands at the opposite end from which the components are being removed and strap the vehicle to the hoist. Does the Scan Tool indicate a vehicle speed above the specified value? | 24 km/h (15 mph) | Go to Intermittent Conditions | |||||||||
3 |
Does the DMM indicate a voltage above the specified value? | 1.2 volts | ||||||||||
4 |
Is the test lamp illuminated? | -- | ||||||||||
5 |
Is the voltage above the specified value? | 0.2 volts | ||||||||||
6 |
Did you find and correct a condition? | -- | ||||||||||
7 | Repair the short to voltage on the VSS high circuit (CKT 821). Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
8 | Repair the open or high resistance in the VSS high circuit (CKT 821). Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
9 |
Important: Inspect the reluctor wheel on the transmission output shaft (2WD) or transfer case output shaft (4WD) for excessive runout, slippage, missing teeth, or damage. Replace the VSS. Refer to the appropriate procedure from the following list:
Is the action complete? | -- | -- | |||||||||
10 | Repair the open in the VSS low circuit (CKT 822). Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls. Is the action complete? | -- | -- | |||||||||
12 |
Has the test run and passed? | -- | System OK |
