GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • 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.

DTC Descriptor

DTC B0560: Tachometer Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Engine Speed Signal

B0560, P0654

B0560, P0654

B0560, P0654

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Circuit Description

The engine control module (ECM)/powertrain control module (PCM) creates the engine speed signal by pulsing the signal circuit to ground at the rate of 2 pulses per engine revolution. The instrument panel cluster (IPC) converts the signal to a tachometer position. The IPC also receives a serial data message from the ECM/PCM indicating the engine speed. The IPC uses the serial data message for diagnostic purposes.

Conditions for Running the DTC

    • The IPC receives a serial data message from the ECM/PCM indicating that the engine speed is greater than 800 RPM.
    • The ignition voltage is between 9-18 volts.

Conditions for Setting the DTC

    • The IPC does not detect a 2 pulses per engine revolution signal on the engine speed signal circuit.
    • The above condition is present for at least 5 seconds.

Action Taken When the DTC Sets

The IPC stores a DTC B0560 in memory.

Conditions for Clearing the DTC

    • A history DTC clears after 100 malfunction free warm-up cycles.
    • The DTC becomes history when the conditions for setting the DTC are no longer present.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the ECM/PCM. Install a signal generator and instrument panel tester between ground and the following engine speed signal circuit:
  2. • Terminal 28 (LF8)
    • Terminal 38 LF6)
    • Terminal 10 (L18)
  3. Ignition ON, set the signal generator to generate a tachometer signal. Verify that the tachometer indicates a RPM reading.
  4. 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 IPC.
  5. 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