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Home >> Cadillac >> 2015 >> CTS Base, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panel System Displays And Gauges (Sedan) >> Diagnostic Information and Procedures >> Tachometer Inaccurate or Inoperative >> Circuit/System Testing

Circuit/System Testing

  1. Ignition ON, verify the tachometer moves from the minimum to the maximum position and back to the minimum position when performing the Instrument Cluster Gauge Sweep Test with the scan tool.
    • If tachometer does not sweep 

      Replace the P16 Instrument Cluster.

    • If speedometer sweeps properly 
  2. Ignition OFF, disconnect the harness connector at the Instrument Cluster.
  3. Test for less than 1 V between the signal circuit 22 and ground.
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • If less than 1 V 
  4. Ignition ON.
  5. Test for greater than 10V between the engine speed signal circuit terminal 22 and ground.
    • If less than 10 V 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the engine speed signal circuit 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 engine speed 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.
    • If greater than 10 V 
  6. Replace the P16 Instrument Cluster.
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