GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The engine control module (ECM) 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 engine speed signal to a tachometer position. The IPC also receives a class 2 message from the ECM indicating the engine speed. The IPC uses this class 2 message for diagnostic purposes.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B0560 Tachometer Circuit

Conditions for Running the DTC

    • The IPC receives a class 2 message from the ECM 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.
    • The IPC receives the clear code command from the scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Start the engine.
  3. With the scan tool, observe the Engine Speed parameter in the engine control module (ECM) Engine Data 1 data list.

Does the engine speed parameter match the tachometer display?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the ECM connector C2.
  3. Turn the ignition ON, with the engine OFF.
  4. Measure the voltage from the engine speed signal circuit of the ECM to a good ground.

Does the voltage measure greater than the specified value?

9 V

Go to Step 4

Go to Step 5

4

Test the engine speed signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

5

Test the engine speed signal circuit for an open or for a short to ground. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

6

Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

7

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 .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 10

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9

Replace the IPC. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 10

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10

  1. Use the scan tool in order to clear the DTCs.
  2. Operate vehicle within the Conditions for Running this DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK