The engine control module (ECM) creates the vehicle speed output signal by pulsing the circuit to ground. The ECM monitors the voltage on the vehicle speed output circuit. If the ECM determines that the voltage is out of the normal operating range, a DTC sets.
This diagnostic procedure supports the following DTC:
DTC P0608 Vehicle Speed Output Circuit
• | The engine speed is more than 400 RPM. |
• | The ignition voltage is between 6-18 volts. |
• | The ECM 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. |
The ECM records the operating conditions at the time the diagnostic fails. The ECM displays the failure information in the Failure Records on the scan tool.
• | 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 PCM receives the clear code command from the scan tool. |
Step | Action | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | |||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Does the Vehicle Speed parameter match the speedometer display? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | ||||||
3 |
Does the vehicle speedometer indicate approximately 55 MPH? | Go to Step 5 | Go to Step 4 | ||||||
4 | Test the vehicle speed signal circuit for the following:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 | ||||||
5 | Inspect for poor connections at harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 | ||||||
6 | Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | ||||||
7 | Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | -- | ||||||
8 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming . Did you complete the replacement? | Go to Step 9 | -- | ||||||
9 |
Does the DTC reset? | Go to Step 2 | System OK |