• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

The engine control module (ECM) creates the engine speed signal by pulsing the engine speed signal circuit at a rate of 2 pulses per engine revolution. The Radio converts the 2 pulses per engine revolution signal to an engine speed value used for active noise cancellation purposes. The ECM monitors the voltage at the engine speed signal circuit to determine when the voltage is out of the normal operating range.

• The engine speed is more than 400 RPM.
• The ignition voltage is between 9–18 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 DTC becomes history when the conditions for setting the DTC are no longer present.
• The history DTC clears after 40 malfunction-free warm-up cycles.

Instrument Cluster Schematics

Master Electrical Component List

Instrument Cluster Description and Operation

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

Control Module References for scan tool information

1. Ignition ON.
2. Verify the tachometer sweeps when performing the scan tool Instrument Cluster Gauge Sweep control function.
• If the tachometer does not sweep

  Replace the P16 Instrument Cluster

• If the tachometer sweeps
3. Engine running, verify the tachometer display matches the scan tool Engine Speed parameter in the ECM Engine Data List.
• If tachometer display does not match the Engine Speed parameter

  Perform Circuit/System Testing.

• If tachometer display matches the Engine Speed parameter
4. All OK.

1. Ignition OFF, disconnect the X1 harness connector at the A11 Radio.
2. Ignition ON, test for 9–11 volts between the engine speed signal circuit terminal 23 and ground.
• If less than 9 volts
1. Ignition OFF, disconnect the appropriate harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit terminal and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the A11 Radio.
• If greater than 11 volts
1. Ignition OFF, disconnect the appropriate harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the A11 Radio.
• If 9–11 volts
3. Test or replace the K20 Engine Control Module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for the control module replacement, programming, and setup