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 Circuit
| P0608
| P0608
| P0608
| --
|
Circuit Description
The engine control module (ECM)/powertrain control module (PCM) creates the vehicle speed output signal by pulsing the circuit to ground. The ECM/PCM monitors the voltage on the vehicle speed output circuit. If the ECM/PCM determines that the voltage is
out of the normal operating range, a DTC sets.
Conditions for Running the DTC
• | The engine speed is more than 400 RPM. |
• | The ignition voltage is between 6-18 volts. |
Conditions for Setting the DTC
• | The ECM/PCM detects that the commanded state of the driver and the actual state of the signal circuit do not match. |
• | The above condition must be present for a minimum of 5 seconds. |
Action Taken When the DTC Sets
The ECM/PCM records the operating conditions at the time the diagnostic fails. The ECM/PCM displays the failure information in the Failure Records on the scan tool.
Conditions for Clearing the MIL/DTC
• | The history DTC clears after 40 malfunction-free warm-up cycles. |
• | The DTC becomes history when the conditions for setting the DTC are no longer present. |
• | The ECM/PCM receives the clear code command from the scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Scan Tool Data List
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECM/PCM. Install a signal generator and instrument panel tester between the vehicle speed signal circuit and ground.
- Ignition ON, set the signal generator to generate a speedometer signal. Verify that the vehicle speedometer indicates a reading.
⇒ | If no speedometer reading is present, test the signal circuit for an open/high resistance, a short to voltage, or a short to ground. If the circuit tests normal, replace the instrument panel cluster (IPC). |
- If all circuits test normal, test or replace the ECM/PCM.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Control Module References
for the ECM/PCM and IPC replacement, setup, and programming