P0598
DTC P0597-P0599
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provide an overview of each diagnostic category.
DTC Descriptors
DTC P0597
-
Engine Coolant Thermostat Heater Control Circuit
DTC P0598
-
Engine Coolant Thermostat Heater Control Circuit Low Voltage
DTC P0599
-
Engine Coolant Thermostat Heater Control Circuit High Voltage
Diagnostic Fault Information
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 [1][2]Electrical Diagrams for the LUW engine
* Engine Controls Schematics [1][2]Electrical Diagrams for the LUV engine
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Cooling System Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References 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 Ignition circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
3. Verify that a test lamp does not illuminate between the low reference circuit terminal 2 and ground.
• If the test lamp illuminates, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
4. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
5. Test for infinite resistance between the control circuit terminals listed below and ground:
* LUV: Control circuit terminal 14 X2
* LUW: Control circuit terminal 43 X1
• If less than the specified value, test the control circuit for a short to ground.
6. Test for less than 5 ohms between the control circuit terminals listed below and control circuit terminal 2 at the E41 Engine Coolant Thermostat Heater harness connector:
* LUV: Control circuit terminal 14 X2
* LUW: Control circuit terminal 43 X1
• If greater than the specified value, test the control circuit for an open/high resistance.
7. If all circuits test normal, replace the E41 Engine Coolant Thermostat Heater.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Engine Coolant Thermostat Replacement (LUV) Engine Coolant Thermostat Replacement (LUW) Service and Repair
* Control Module References Control Module References for ECM replacement, programming and setup