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Home >> Chevrolet >> 2021 >> Camaro SS, 2D Convertible, Automatic Trans >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Displays And Gauges >> Diagnostic Information and Procedures >> Tachometer Inaccurate or Inoperative >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the X1 harness connector at the P16 Instrument Cluster, engine Running.
  2. Test for 15 - 30 Hz DC between the signal circuit terminal 22 and ground.
    • If not between 15 - 30 Hz DC 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    3. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance.
    4. 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 K20 Engine Control Module.
    • Go to next step: If between 15 - 30 Hz DC 
  3. Engine running. Verify the scan tool Instrument Cluster Engine Speed parameter aligns with actual engine speed.
    • If parameter does not align with engine RPM 

      Verify Engine Control Module, Transmission Control Module (if equipped), Instrument Cluster, and Serial Data Gateway Module communicate on their appropriate communication buses. Refer to Symptoms - Data Communications

    • Go to next step: If parameter aligns with engine RPM 
  4. Replace the P16 Instrument Cluster.
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