Diagnostic Instructions
DTC Descriptor
DTC P0608: Vehicle Speed Output Circuit
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Vehicle Speed Signal or Sensor Correlation
| P0608
| P0608
| P0608
| P2162
|
Circuit/System Description
The vehicle speed signal circuit is an input to the throttle actuator control (TAC) module from the powertrain control module (PCM). The PCM provides a constant voltage signal on the vehicle speed signal circuit. The PCM creates the vehicle speed signal
by internally pulsing the vehicle speed signal to ground. The TAC module uses the vehicle speed signal from the PCM, in order to determine the vehicle speed. The TAC module then sends a serial data message to the PCM indicating the vehicle speed that the TAC
module has detected.
Conditions for Running the DTC
| • | The vehicle is in Drive or Reverse. |
| • | The vehicle speed is greater than 8 km/h (5 mph). |
| • | There are no current VSS DTCs present. |
| • | The ignition voltage is between 9-16 volts. |
Conditions for Setting the DTC
| • | The PCM sends a 8 km/h (5 mph) signal on the vehicle speed signal circuit to the TAC module. The TAC module sends a serial data message to the PCM indicating that the vehicle speed is 0 km/h (0 mph). |
| • | The above condition is present for greater than 4 seconds. |
Actions Taken When the DTC Sets
| • | The cruise control system is disabled. |
| • | The malfunction indicator lamp (MIL) will illuminate. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | A history DTC will clear after 40 malfunction-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Connector End View Reference
Component Connector End Views
Description and Operation
Cruise Control Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the TAC module.
- Ignition ON, test for 8.0-9.0 volts between the signal circuit terminal 4 and ground.
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the PCM. |
| ⇒ | If less than the specified value, test the signal circuit for a short to ground
or an open/high resistance. If the circuit tests normal, replace the PCM. |
- If all circuits test normal, replace the TAC module.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for PCM or TAC module replacement, setup, and programming
