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DTC P0597-P0599

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 provide an overview of each diagnostic category.

DTC Descriptor

DTC P0597 00: Engine Coolant Thermostat Heater Control Circuit

DTC P0598 00: Engine Coolant Thermostat Heater Control Circuit Low Voltage

DTC P0599 00: Engine Coolant Thermostat Heater Control Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Control High

P0597 00, P0598 00

P0597 00, P0598 00

-

-

Control Low

P0598 00

P0598 00

P0597 00, P0599 00

-

Circuit/System Description

The engine control module (ECM) controls the pulse width modulated (PWM) thermostat. The engine coolant thermostat heater controls coolant flow and regulates the engine operating temperature. The ECM supplies 12 V to the thermostat. The ECM controls the engine coolant thermostat heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

Conditions for Running the DTC

    • The ignition is ON or the engine is running.
    • The ignition voltage is greater than 9 V.
    • DTC P0597 00, P0598 00, and P0599 00 run continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 15 s.

Action Taken When the DTC Sets

DTC P0597 00, P0598 00, P0599 00 are Type B DTCs.

Conditions for Clearing the DTC

DTC P0597 00, P0598 00, P0599 00 are Type B DTCs.

Diagnostic Aids

The engine coolant thermostat heater has a mechanical fail-safe in case of an electrical condition with the engine coolant thermostat heater. The mechanical thermostat will open at approximately 104°C (220°F). The mechanical thermostat will cycle from approximately 104°C (220°F) to approximately 98°C (208°F). The heater is part of the thermostat. The engine coolant thermostat heater and the thermostat housing are serviced as an assembly.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the E41 Engine Coolant Thermostat Heater.
  2. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 2 and ground.
  3. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
  4. Verify that a test lamp does not illuminate between the control circuit terminal 1 and ground.
  5. If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
  6. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
  7. Test for infinite resistance between the control circuit terminal X2 10 and ground.
  8. If less than the specified value, test the control circuit for a short to ground.
  9. Test for less than 5 Ω between the control circuit terminal X2 70 at the K20 Engine Control Module harness connector and terminal 1 at the E41 Engine Coolant Thermostat Heater harness connector.
  10. If greater than the specified value, test the control circuit for an open/high resistance.
  11. If all circuits test normal, replace the E41 Engine Coolant Thermostat Heater.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Engine Coolant Thermostat Replacement : 2.0L Diesel LNP → 1.6L LDE, LXV, 1.8L LUW, 2H0 and LFH
    • Control Module References for ECM replacement, setup, and programming
   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved