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 this generates an AC voltage pulse. As the vehicle speed increases the AC voltage pulse rate also increases.
The PCM supplies this signal to the BCM and the instrument cluster.
Conditions for Setting the DTC
| • | DTCs P0107, P0108, P0117, P0118, P0506, P0507, P1120, P1220, P1221 are not set. |
| • | ECT is greater than 35°C (95°F) |
| • | Engine speed is greater than 1000 RPM. |
| • | TP sensor angle is greater than 10%. |
| • | MAP is greater than 40 kPa when A/C is OFF. |
| • | MAP is greater than 45 kPa when A/C is ON. |
| • | All conditions met for 2 seconds. |
| • | PCM detects vehicle speed at 0 km/h (0 mph) for 50 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
Inspect all of the circuits to the PCM and the VSS. Inspect the terminal connections at the VSS harness connector and at the PCM harness connector. If all of the circuits and connections are OK, replace the PCM.
For intermittents, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check ? | -- | ||
|
Important: DO NOT perform this test on vehicles with Independent Suspension without supporting the lower control arms so that the drive axles are in a normal horizontal position. Running the vehicle with the wheels hanging down at full travel may damage the drive axles.
Does the scan tool indicate a vehicle speed above the specified value? | 0.0 mph (0.0 km/h) | Refer to Diagnostic Aids | ||
3 |
Does the scan tool indicate a vehicle speed above the specified value? | 0.0 mph (0.0 km/h) | ||
4 | Repair the faulty VSS connection or faulty VSS. Is the action complete? | -- | -- | |
5 | Measure the voltage from the VSS signal circuit to a known good ground using the DMM J 39200 . Does the DMM indicate the specified value? | 5.0 V | ||
6 | Measure the voltage from the VSS signal circuit to the VSS ground circuit using the DMM J 39200 . Does the DMM indicate the specified value? | 5.0 V | ||
7 | Check the calibration ID for the most current and/or incorrect calibration. Is the most current and proper calibration present? | -- | ||
8 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Replace the PCM. Is the action complete? | -- | -- | |
9 | Repair the signal circuit to the vehicle speed sensor. Is the action complete? | -- | -- | |
10 | Repair the ground circuit to the vehicle speed sensor. Is the action complete? | -- | -- | |
11 | Install proper calibration and/or most current. Is the action complete? | -- | -- | |
12 |
Does the scan tool indicate that this test ran and passed? | -- | ||
13 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
