| • | Perform the Diagnostic System Check - Vehicle prior to using the diagnostic procedure. | 
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. | 
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. | 
Circuit  | Short to Ground  | Open/High Resistance  | Short to Voltage  | Signal Performance  | 
|---|---|---|---|---|
Engine Speed Signal  | B0560  | B0560  | B0560  | --  | 
The engine control module (ECM) creates the engine speed signal by pulsing the engine speed signal circuit to ground at a rate of 2 pulses per engine revolution. The instrument panel cluster (IPC) converts the engine speed signal to a tachometer position to indicate the engine speed. The IPC also receives from the ECM a serial data message indicating the engine speed. The IPC uses the serial data engine speed information from the ECM for diagnostic purposes.
| • | The engine speed is greater than 800 RPM. | 
| • | The ignition voltage is between 9-18 volts. | 
| • | The IPC detects that the engine speed signal circuit does not match the engine speed from the serial data circuit. | 
| • | The above condition is present for at least 5 seconds. | 
The IPC stores the DTC in memory.
| • | A last test failed (current DTC) clears when the diagnostic runs and does not fail. | 
| • | A history DTC clears after 40 malfunction-free warm-up cycles. | 
Instrument Cluster Description and Operation
Control Module References for scan tool information
| ⇒ | If no RPM reading is present, test the signal circuit for a short to voltage, a short to ground or an open/high resistance. If the circuit tests normal, replace the IPC. | 
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for the ECM and IPC replacement, setup, and programming