GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • 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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Coolant Level Switch Signal

Indicator OFF

Indicator ON

--

--

Ground

--

Indicator ON

--

--

Circuit/System Description

The low engine coolant level indicator is controlled by the HVAC control module. The normal state of the engine coolant level switch is closed when in contact with coolant.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

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

Circuit/System Verification

The low coolant indicator should be OFF with the engine coolant at the proper level.

Circuit/System Testing

Important: Circuit/System Verification must be performed before performing the Circuit/System Testing.

  1. Ignition OFF, disconnect the harness connector at the coolant level switch.
  2. Install a 3A fused jumper wire between the signal circuit terminal and ground.
  3. Engine running, verify the low coolant indicator turns OFF.
  4. If the indicator does not turn OFF, test the signal circuit for an open/high resistance.
    If the indicator turns OFF, test the ground circuit for an open/high resistance.
  5. If all circuits test normal, replace the coolant level switch.

Repair Instructions

    •  Radiator Surge Tank Replacement
    •  Control Module References
    •  Instrument Cluster Replacement

Repair Verification

Verify that the low coolant indicator is OFF with the engine coolant at the proper level.