Engine Cooling System: Diagnosis Chevrolet Malibu VIII рестайлинг

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Typical Scan Tool Data

Radiator Coolant Temperature Sensor

Conditions for Running the DTC

P00B3

1. The engine run time is greater than 10 s.
2. The intake air temperature (IAT) is colder than 70°C (158°F).
3. The DTC runs continuously when the above conditions are met.

P00B4

1. The engine run time is greater than 60 s.
2. The intake air temperature (IAT) is warmer than -7°C (19°F).
3. The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P00B3

The ECM detects that the RCT sensor is warmer than 149°C (300°F) for greater than 10 s.

P00B4

Note. The scan tool only displays to -40°C (-40°F).

The ECM detects that the RCT sensor is colder than -60°C (-76°F) for greater than 10 s.

Action Taken When the DTC Sets

1. DTCs P00B3 and P00B4 are Type B DTCs.
2. The cooling fans will be commanded ON by the ECM.
3. The engine coolant temperature gauge is inoperative.

Conditions for Clearing the MIL/DTC

P00B3 and P00B4 are Type B DTCs.

Diagnostic Aids

Note. The engine coolant temperature (ECT) sensor is mounted on the engine and the radiator coolant temperature (RCT) sensor is mounted on the radiator.

1. As the thermostat opens, the RCT sensor temperature should rise steadily, then stabilize once the thermostat opens completely.
2. Test the RCT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor.
3. If the vehicle has sat for greater than 8 hours, the ECT sensor and the RCT sensor values should display within 3°C (5°F).

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B34B Engine Coolant Temperature Sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohms between the low reference terminal 2 and ground. If 5 ohms or greater Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 5 ohms
3. Ignition ON.
4. Verify the scan tool Radiator Coolant Temperature Sensor parameter is colder than -39°C (-38°F). If warmer than -39°C (-38°F) Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If colder than -39°C (-38°F)
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
6. Verify the scan tool Radiator Coolant Temperature Sensor parameter is warmer than 149°C (300°F). If colder than the 149°C (300°F) Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module, Ignition ON. 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 Ignition OFF. Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If warmer than 149°C (300°F)
7. Test or replace the B34B Engine Coolant Temperature Sensor.

Component Testing

1. Ignition OFF, disconnect the harness connector at the B34 Engine Coolant Temperature Sensor.
2. Test the RCT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the «Temperature Versus Resistance»(ref-609148-S04084917612014041500000) table. The resistance values should be in range of the table values. If not within the specified range Replace the B34 Engine Coolant Temperature Sensor. If within the specified range
3. Test for infinite resistance between each terminal and the sensor housing. If less than infinite resistance Replace the B34 Engine Coolant Temperature Sensor. If infinite resistance
4. All OK.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

Radiator Coolant Temperature Sensor

Circuit Description

The engine control module (ECM) monitors the temperature of the engine radiator coolant. The ECM controls the thermostat with a pulse width modulated (PWM) signal. The ECM compares the radiator coolant temperature to the engine coolant temperature in order to determine if there sufficient coolant flow through the thermostat.

1. DTCs P00B3, P00B4, P0117, P0118, P111E, and P112F are not set.
2. The engine run time is greater than 5 m. OR
3. The engine coolant temperature is greater than 99°C (211°F).
4. The DTC runs continuously when the above conditions are met.

Note. The scan tool display range is between -40 and + 150°C (-40 and +302°F).

The ECM detects the difference between the RCT sensor and the ECT sensor is greater than 30°C (86°F) when the ECT sensor is warmer than 117°C (242°F) for greater than 5 s.

DTC P00B7 is a Type B DTC.

DTC P00B7 is a Type B DTC.

1. The thermostat has a mechanical fail-safe in case of an electrical condition with the thermostat heater. The mechanical thermostat will start to open at approximately 97°C (206°F).
2. A resistance condition in the RCT sensor circuits may cause this DTC. This condition results in a greater voltage on the RCT sensor signal circuit, which is interpreted by the ECM as a colder RCT.

1. Ignition OFF, inspect the cooling system for the following conditions: Weak coolant solution Obstructed radiator air flow or bent radiator fins Blocked cooling system passages Radiator hoses that are restricted, collapsed, or deteriorated Damaged water pump Loss of cooling system pressure Leaking surge tank cap Leaking radiator hoses Cylinder head or an engine block that is cracked or plugged If a condition is found Repair or replace the affected component as necessary. If no condition is found
2. All OK.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

1. The ignition voltage is greater than 11 volts.
2. The ECM driver transitions from ON to OFF or from OFF to ON.
3. DTCs P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

1. The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
2. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relays 2 and 3 operates one fan at a high speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed

1. Ignition OFF, disconnect all of the cooling fan relays. Ignition ON.
2. Verify that a test lamp illuminates between ground and a relay coil ignition circuit terminal listed below: KR20C Cooling Fan Low Speed Relay terminal 85/2 KR20D Cooling Fan High Speed Relay terminal 86/1 KR20E Cooling Fan Speed Control Relay terminal 86/1 If the test lamp does not illuminate Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Remove the test lamp. Test for less than 2 ohms in the ignition circuit of the appropriate cooling fan relay, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Remove the test lamp. Test for infinite resistance between the appropriate cooling fan relay ignition circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance test or replace the appropriate cooling fan relay. If the test lamp illuminates
3. Ignition ON.
4. Connect a DMM, set on the diode setting, between ground and a relay control circuit terminal listed below: KR20C cooling fan low speed relay terminal 86/1 KR20D cooling fan high speed relay terminal 85/2 KR20E cooling fan speed control relay terminal 85/2
5. Verify the DMM reading is greater than 2.5 V or displays O.L with the cooling fan relays commanded OFF with a scan tool. If 2.5 V or less Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module. Test for infinite resistance between the appropriate relay coil control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If greater than 2.5 V or displays O.L.
6. Verify the DMM reading is less than 1 V when commanding the cooling fan relays ON with a scan tool. If 1 V or greater Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the appropriate cooling fan relay control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 ohms in the appropriate cooling fan relay control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 1 V
7. Test or replace the appropriate cooling fan relay.

1. Ignition OFF.
2. Disconnect a cooling fan relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. If less than 70 ohms or greater than 110 ohms Replace the cooling fan relay. If between 70-110 ohms
4. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 OR 3 and 2 3 and 5 3 and 1 1 and 5 If less than infinite resistance Replace the cooling fan relay. If infinite resistance
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4. If 2 ohms or greater Replace the KR20E Cooling Fan Speed Control Relay. If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 5/87. If 2 ohms or greater Replace the cooling fan relay. If less than 2 ohms
9. All OK.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

Conditions for Running the DTCs

1. The ignition is ON, or the engine is running.
2. The DTCs run continuously once the above condition is met

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 seconds.

1. DTCs P0597, P0598, and P0599 are Type B DTCs.
2. The engine control module commands the engine cooling fans ON.

Conditions for Clearing the DTC

DTCs P0597, P0598, and P0599 are Type B DTCs.

1. A low engine coolant level could cause the thermostat heater to overheat and set a DTC.
2. The thermostat has a mechanical fail-safe in case of an electrical condition with the thermostat heater. The mechanical thermostat will open at approximately 80°C (176°F). The mechanical thermostat will cycle from approximately 85°C (185°F) to approximately 102°C (215°F).

1. Ignition OFF, disconnect the harness connector at the E41 Engine Coolant Thermostat Heater, Ignition ON.
2. Verify that a test lamp illuminates between the ignition circuit terminal 1 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF . Test for less than 2 ohms in the ignition circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF . Test for infinite resistance between the ignition circuit and ground. If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance, test all the components connected to fuse and replace as necessary. If the test lamp illuminates
3. Connect a test lamp between the ignition circuit terminal 1 and the control circuit terminal 2, command the Engine Coolant Thermostat Heater to Increase to 100 % and Decrease to 0 % with a scan tool.
4. Verify that a test lamp turns On and OFF. If the test is always ON Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If the test lamp is always OFF Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms replace the K20 Engine Control Module If the test lamp turns On and OFF
5. Test or replace the E41 Engine Coolant Thermostat Heater.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

Radiator Coolant Temperature Sensor

The engine coolant radiator temperature sensor is a variable resistor that measures the temperature of the engine coolant in the radiator. The engine control module (ECM) supplies 5 volts to the engine coolant radiator temperature signal circuit and supplies a ground to the low reference circuit. The purpose of this diagnostic is to determine if the input from the RCT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the engine is OFF. If the required engine OFF time is met at start-up, the ECM will compare the temperature difference between the actual measured RCT and ECT sensors.

The following table illustrates the difference between temperature, resistance, and voltage

1. DTCs P00B3, P00B4, P0112, P0113, P0117, P0118, P0502, P0503, P111E or P2610 are not set.
2. The vehicle has been OFF for greater than 8 hours before vehicle ON.
3. The engine is running.
4. The intake air temperature (IAT) is warmer than -7°C (19°F).
5. The fuel level is greater than 10 percent.
6. The DTC runs once per ignition cycle when the above conditions are met.

The ECM determines the absolute difference of temperature between the RCT start up temperature and ECT start up temperature is greater than 20°C (68°F) .

DTC P112F is a Type B DTC.

DTC P112F is a Type B DTC.

1. As the thermostat opens, the radiator coolant temperature sensor signal should rise steadily, then stabilize once the thermostat opens completely.
2. Inspect for the correct operation of the engine cooling system and verify the correct coolant level.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B34B Engine Coolant Temperature Sensor 2. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohms between the low reference terminal 2 and ground. If 5 ohms or greater Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 5 ohms
3. Ignition ON.
4. Verify the scan tool Radiator Coolant Temperature Sensor parameter is colder than -39°C (-38°F). If warmer than -39°C (-38°F) Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If colder than -39°C (-38°F)
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
6. Ignition ON, Verify the scan tool Radiator Coolant Temperature Sensor parameter is warmer than 140°C (284°F). If colder than the 140°C (284°F) Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, Ignition ON. 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 Ignition OFF Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If warmer than 140°C (284°F)
7. Test or replace the B34B Engine Coolant Temperature Sensor 2.

1. Vehicle OFF, remove the B34B Engine Coolant Temperature Sensor.
2. Test the engine coolant temperature sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the «Temperature Versus Resistance»(ref-609148-S04084917612014041500000) table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the B34B Engine Coolant Temperature Sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

1. DTCs P00B3, P00B4, P0101, P0102, P0103, P0111, P0112, P0113, P0114, P0117 , P0118, P111E or P112F are not set.
2. The engine run time is between 70 s and 30 min.
3. The engine coolant temperature (ECT) sensor at start-up is between -10°C to +59°C (14°F to 138°F).
4. The intake air temperature (IAT) sensor is between -7°C to +60°C (-4°F to +140°F).
5. The airflow into the engine is between 1 to 100 g/s.
6. The DTC runs once per ignition cycle when the above conditions are met.

The ECM detects the engine coolant thermostat is stuck open for at least 2.5 min.

DTC P2181 is a Type B DTC

DTC P2181 is a Type B DTC

1. Insufficient vehicle interior heating is an indication of improper thermostat operation.
2. The scan tool Desired ECT Sensor and the ECT Sensor parameters should be within 5°C (9°F) when the engine is at operating temperature.
3. A resistance condition in the ECT sensor circuits may cause this DTC. This condition results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT.

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following

1. Perform «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) and verify all of the following items: Engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly. There are no diagnostic trouble codes (DTCs) stored. Scan tool data is within a normal operating range.
2. Verify the customer concern.
3. Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.
4. Locate the correct symptom. Perform the tests and inspections associated with the symptom.

Review the entire cooling system operation in order to familiarize yourself with the system functions. Refer to Cooling Fan Description and Operation , and Cooling System Description and Operation .

Visual/Physical Inspection

Several of the symptom procedures call for a careful visual and physical inspection. This can lead to correcting a condition without further tests and can save time. This inspection should include the following

1. Ensure that the control module grounds are clean, tight, and correctly located.
2. Inspect cooling system hoses and pipes for splits, kinks, and improper connections. Inspect thoroughly for any type of leak or restriction.
3. Inspect for a dirty or restricted radiator or HVAC condenser.
4. Inspect for aftermarket devices which could affect the operation of the cooling system.
5. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
6. Inspect the coolant recovery reservoir for proper coolant level.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Cooling Fan Always On»(ref-609148-S15032994192014041500000)
2. «Cooling Fan Inoperative»(ref-609148-S28948602692014041500000)
3. «Engine Overheating»(ref-609148-S14156667502014041500000)
4. «Loss of Coolant»(ref-609148-S07951242992014041500000)
5. «Thermostat Diagnosis»(ref-609148-S02837693242014041500000)
6. «Engine Fails To Reach Normal Operating Temperature»(ref-609148-S17412699502014041500000)

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relays 2 and 3 operates one fan at a high speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed
2. Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. If this condition is suspected, refer to the temperature versus resistance tables in the appropriate Engine Controls subsection.

Both Cooling Fans Always ON

1. Ignition OFF, disconnect KR20C Cooling Fan Low Speed Relay, ignition ON.
2. Verify that both cooling fans are OFF. If the cooling fans are ON Ignition OFF, disconnect the harness connector at the G10R Cooling Fan Motor-Right, ignition ON. Test for less than 1 V between KR20C Cooling Fan Low Speed Relay terminal 87/5 and ground. If 1 V or greater, repair the short to voltage in the relay controlled output circuit. If the cooling fans are OFF
3. Test or replace the KR20C Cooling Fan Low Speed Relay.

One Cooling Fan Always ON

1. Ignition OFF, disconnect the KR20D Cooling Fan High Speed Relay, ignition ON.
2. Verify the cooling fan is OFF. If the cooling fan is ON Ignition OFF, disconnect the harness connector at the G10L Cooling Fan Motor-Left, ignition ON. Test for less than 1 V between KR20D Cooling Fan High Speed Relay terminal 30/3 and ground. If 1 V or greater, repair the short to voltage in the relay controlled output circuit. If the cooling fan is OFF
3. Test or replace the KR20D Cooling Fan High Speed Relay.

1. Ignition OFF.
2. Disconnect a KR20 Cooling Fan Relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. If less than 70 ohms or greater than 110 ohms Replace the KR20 cooling fan relay. If between 70-110 ohms
4. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 OR 3 and 2 3 and 5 3 and 1 1 and 5 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4. If 2 ohms or greater Replace the KR20E Cooling Fan Speed Control Relay. If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 5/87. If 2 ohms or greater Replace the KR20 Cooling Fan Relay. If less than 2 ohms
9. All OK.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relays 2 and 3 operates one fan at a high speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed

1. Ignition OFF, disconnect all of the KR20 Cooling Fan Relays.
2. Verify a test lamp illuminates between ground and the B+ circuit terminals listed below: KR20C Cooling Fan Low Speed B+ circuit terminal 30/3 KR20D Cooling Fan High Speed B+ circuit terminal 87/5 If the test lamp does not illuminate and the circuit fuse is good Disconnect the appropriate cooling fan fuse. Test for less than 2 ohms between the fuse and the appropriate relay B+ circuit terminal, end to end. If 2 ohms or greater, repair the open/high resistance in the B+ circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Connect a DMM to the appropriate relay B+ circuit terminal. Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the B+ circuit. If infinite resistance Disconnect the harness connector at the appropriate G10 Cooling Fan Motor. Test for infinite resistance between the appropriate relay controlled output circuit terminal 87/5 and ground. KR20C Cooling Fan Low Speed output circuit terminal 87/5 KR20D Cooling Fan High Speed output circuit terminal 30/3 If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, test or replace the appropriate G10 Cooling Fan Motor. If the test lamp illuminates
3. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the G10L Cooling Fan Motor-Left. It may take up to 2 minutes for all vehicle systems to power down.
4. Test for less than 5 ohms between the circuits listed below and ground: G10L Cooling Fan Motor-Left terminal A KR20E Cooling Fan Speed Control Relay terminal 87/5 If 5 ohms or greater Ignition OFF and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 ohms in the appropriate ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 5 ohms
5. Connect the harness connector at the G10L Cooling Fan Motor-Left.
6. Connect a 50 A fused jumper between the KR20D Cooling Fan High Speed Relay terminals 30/3 and 87/5.
7. Verify the G10L Cooling Fan Motor-Left is activated at high speed. If the cooling fan does not activate Disconnect the harness connector at the G10L Cooling Fan Motor-Left. Test for less than 2 ohms in the circuit between KR20D Cooling Fan High Speed Relay terminal 30/3 and the G10L Cooling Fan Motor-Left terminal B. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the G10L Cooling Fan Motor-Left. If the cooling fan activates
8. Connect a fused jumper between the KR20E Cooling Fan Speed Control Relay switch circuit terminal 30/3 and the ground circuit terminal 87/5.
9. Connect a 40 A fused jumper between the KR20C Cooling Fan Low Speed Relay terminals 30/3 and 87/5.
10. Verify the G10R Cooling Fan Motor-Right is activated at high speed. If the cooling fan does not activate Disconnect the harness connector at the G10R Cooling Fan Motor-Right. Test for less than 2 ohms in the circuit between KR20C Cooling Fan Low Speed Relay terminal 87/5 and the G10R Cooling Fan Motor-Right terminal B. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms Test for less than 2 ohms in the circuit between KR20E Cooling Fan Speed Control Relay terminal 30/3 and the G10R Cooling Fan Motor-Right terminal A. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the G10R Cooling Fan Motor-Right. If the cooling fan activates
11. Install the KR20E Cooling Fan Speed Control Relay.
12. Verify both fan motors activate at low speed. If both cooling fans do not activate at low speed Disconnect both cooling fan motor harness connectors and the KR20E Cooling Fan Speed Control Relay. Test for less than 2 ohms in circuit between KR20E Cooling Fan Speed Control Relay terminal 87A/4 and the G10L Cooling Fan Motor-Left terminal B. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms Test for infinite resistance between KR20E Cooling Fan Speed Control Relay terminal listed below and ground. KR20E Cooling Fan Speed Control Relay terminal 30/3 KR20E Cooling Fan Speed Control Relay terminal 87A/4 If less than infinite, repair the short to ground in the circuit. If infinite, replace the KR20E cooling fan speed control relay. If both cooling fans activate
13. Test or replace the cooling fan relay listed below as appropriate: KR20C Cooling Fan Low Speed Relay KR20D Cooling Fan High Speed Relay

1. Ignition OFF.
2. Disconnect a KR20 Cooling Fan Relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. If less than 70 ohms or greater than 110 ohms Replace the KR20 cooling fan relay. If between 70-110 ohms
4. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 OR 3 and 2 3 and 5 3 and 1 1 and 5 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4. If 2 ohms or greater Replace the KR20E Cooling Fan Speed Control Relay. If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 87/5. If 2 ohms or greater Replace the KR20 Cooling Fan Relay. If less than 2 ohms
9. All OK.

Thermostat Diagnosis

Thermostat Diagnosis

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

Note. The coolant heater cord will read Open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).

1. Ignition OFF, disconnect the coolant heater cord from the E19 Coolant Heater.
2. Test for 40-55 ohms between the terminals of the E19 Coolant Heater. If not within 40-55 ohms Replace the E19 Coolant Heater. If within 40-55 ohms
3. Test for infinite resistance between each terminal of the E19 Coolant Heater and ground. If less than infinite resistance Replace the E19 Coolant Heater. If infinite resistance
4. Test or replace the coolant heater cord.

1. Perform the «Diagnostic System Check - Vehicle»(ref-609122-S25539464382014041500000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-609122-S25032153612014041500000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-609122-S11603450302014041500000) provides an overview of each diagnostic category.

Note. The coolant heater cord will read Open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).

1. Ignition OFF, disconnect the coolant heater cord from the E19 Coolant Heater.
2. Test for 30-40 ohms between the terminals of the E19 Coolant Heater. If not within 30-40 ohms Replace the E19 Coolant Heater. If within 30-40 ohms
3. Test for infinite resistance between each terminal of the E19 Coolant Heater and ground. If less than infinite resistance Replace the E19 Coolant Heater. If infinite resistance
4. Test or replace the coolant heater cord.

Thermostat Test Procedure Using Tempil Sticks

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a pencil like device. It has a wax material containing certain chemicals which melt at a given temperature. Take a 87°C (188°F) tempil stick or a 97°C (206°F) tempil stick and rub it on the thermostat housing. Temperature sticks can be used to determine a thermostat's operating range.

1. Use a GE 24731 Tempil Stick in order to find the opening and the closing temperatures of the coolant thermostat. The 188 tempil stick melts at 87°C (188°F). The thermostat should begin to open. The 206 tempil stick melts at 97°C (206°F). The thermostat should be fully open.
2. Replace the coolant thermostat if it does not operate properly between this temperature range.

Thermostat Test Procedure Using Glycol

Inspect the operation of the thermostat by hanging the thermostat on a hook in a 50/50 percent solution of DEX-COOL® and clean drinkable water.

In order to inspect if the thermostat valve is opening properly, perform the following test

1. Completely submerge the thermostat in the glycol solution. The solution should be 11°C (22°F) above the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should open.

In order to inspect if the thermostat valve is closing properly, perform the following test

1. Completely submerge the thermostat in a glycol solution. The solution should be 6°C (10°F) below the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should close completely.

Pressure Cap Testing

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the EN-24460-A Cooling System Pressure Tester (1) with GE-42401-A Radiator Cap / Surge Tank Test Adapter (2) in order to test the pressure cap.
4. Test the pressure cap for the following conditions: Pressure release when the EN-24460-A Cooling System Pressure Tester exceeds the pressure rating of the pressure cap. Maintain the rated pressure for at least 10 seconds. Note the rate of pressure loss.
5. Replace the pressure cap under the following conditions: The pressure cap does not release pressure which exceeds the rated pressure of the cap. The pressure cap does not hold the rated pressure.

Cooling System Leak Testing

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(ref-609148-S28355648252014041500000) .
3. Wash the pressure cap mating surface with water.
4. Use the EN-24460-A Cooling System Pressure Tester (1) with GE-42401-3 Radiator Cap/Surge Tank Test Adapter (2) in order to apply pressure to the cooling system. Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gauge for any pressure loss.
6. Repair any leaks as required.