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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 1 (Displays And Gauges) >> Diagnostic Information and Procedures >> Engine Coolant Level Indicator Malfunction (LWN) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

Verify proper engine coolant level before continuing with diagnosis.

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B33 Engine Coolant Level Switch. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 5 Ω between the ground circuit terminal B (or 2) and ground.
    • If 5 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the P16 Instrument Cluster.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • Go to next step: If less than 5 Ω 
  3. Ignition ON.
  4. Verify the scan tool Coolant Level Switch parameter reads OPEN.
    • If the Coolant Level Switch parameter reads CLOSED 
    1. Ignition OFF, disconnect the harness connector at the P16 Instrument Cluster.
    2. Test for infinite resistance between the signal circuit terminal A (or 1) and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the P16 Instrument Cluster.
    • Go to next step: If the Coolant Level Switch parameter reads OPEN 
    5. NOTE:

    If a short to voltage is found on the signal circuit, the fuse in the 3A jumper wire will open.

  5. Install a 3A fused jumper wire between the signal circuit terminal A (or 1) and the ground circuit terminal B (or 2).
  6. Verify the scan tool Coolant Level Switch parameter reads CLOSED.
    • If the Coolant Level Switch parameter reads OPEN 
    1. Ignition OFF, disconnect the harness connector at the P16 Instrument Cluster, ignition ON.
    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.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance on the circuit.
      • If less than 2 Ω, replace the P16 Instrument Cluster.
    • Go to next step: If the Coolant Level Switch parameter reads CLOSED 
  7. Test or replace the B33 Engine Coolant Level Switch.
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