Diagnostic Instructions
DTC Descriptor
DTC P0654: Engine Speed Output Circuit
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Engine Speed Signal Circuit
| P0654
| P0654
| P0654
| --
|
Circuit Description
The powertrain control module (PCM) creates the engine speed signal by pulsing the circuit to ground. The engine control module (ECM)/PCM monitors the voltage on the engine speed signal circuit. If the ECM/PCM determines that the voltage is not within
the normal operating range, the ECM/PCM sets a DTC.
Conditions for Running the DTC
| • | The engine speed is greater than 400 RPM. |
| • | The ignition voltage is greater than 6 volts, but less than 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 exists for a minimum of 5 seconds. |
Action Taken When the DTC Sets
| • | The ECM/PCM stores the DTC information in memory when the diagnostic test runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM/PCM records the operating conditions at the time when the diagnostic test fails. The ECM/PCM stores this information in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | A history DTC is cleared after 40 consecutive malfunction-free warm-up cycles. |
| • | 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 engine speed signal circuit and ground.
- Ignition ON, set the signal generator to generate a tachometer signal. Verify that the tachometer indicates a RPM reading.
| ⇒ | If no RPM 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
