Engine Cooling System: Diagnosis GMC Yukon III

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Typical Scan Tool Data

FC Relay 1, and FC Relay 2 and 3 Ckt Open, Short Gnd, and Short Volts Test Status

Conditions for Running the DTC

1. The system voltage is between 9-18 volts.
2. The engine speed is greater than 400 RPM.
3. DTCs P0480 and P0481 run continuously when the conditions above are met.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480 and P0481 are Type B DTCs.

Diagnostic Aids

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: Fan Relay 1 operates both fans at a low speed Fan Relay 2 and 3 operates one fan at high speed Fan Relays 1, 2, and 3 operates both fans at high speed

Circuit/System Testing

1. Ignition OFF, disconnect the 3 cooling fan relays listed below. FAN LO relay FAN CNTRL relay FAN HI relay
2. Ignition ON, verify that a test lamp illuminates between ground and the ignition circuit terminal 85 of each relay. If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.
3. Set the DMM on the diode setting. Connect the black lead to ground. Connect the red lead of the DMM to a control circuit terminal listed below: FAN LO Relay terminal 86 FAN CNTRL Relay terminal 86 FAN HI Relay terminal 86 The DMM should display OL. If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
4. Command the appropriate cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. If all circuits test normal, test or replace the appropriate KR20 relay.

Component Testing

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the KR20 cooling fan relay.
4. Test the KR20 Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the fan control relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

FC Relay 1, 2 and 3 Ckt Open, Short Gnd, and Short Volts Test Status

1. The ignition voltage is between 11-32 volts.
2. The engine speed is greater than 0 RPM.
3. DTC P0480, P0481, and P0482 run continuously when the conditions above are met.

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

DTCs P0480, P0481 and P0482 are Type B DTCs.

DTCs P0480, P0481 and P0482 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: Fan Relay 1 operates both fans at a low speed. Fan Relay 2 operates both fans at medium speed. Fan Relays 1, 2, and 3 operates both fans at high speed.

1. Ignition OFF, open the hood to disable the Auto-Stop function.
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «DTC P254F»(ref-364537-S27064801832010063000000) .
3. Ignition OFF, disconnect all 5 cooling fan relays.
4. Ignition ON, verify that a test lamp illuminates between ground and the ignition circuit terminal of each relay listed below: FAN LO Relay terminal 85 FAN MID 1 Relay terminal 85 FAN CNTRL Relay terminal 86 FAN MID 2 Relay terminal 86 FAN HI Relay terminal 86 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 and the ignition circuit fuse is open, test all the components connected to the ignition voltage circuit and replace as necessary.
5. Set the DMM on the diode setting. Connect the black lead to ground. Connect the red lead of the DMM to a control circuit terminal listed below: FAN LO Relay terminal 86 FAN MID 1 Relay terminal 86 FAN CNTRL Relay terminal 85 FAN MID 2 Relay terminal 85 FAN HI Relay terminal 85 The DMM should display OL. If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
6. Command the appropriate cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
7. If all circuits test normal, test or replace the appropriate KR20 relay.

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 50-90 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the KR20 cooling fan relay.
4. Test the KR20E Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the KR20E cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The engine is operating.

1. DTC P1258 is a Type A DTC.
2. The engine will operate in the Overheated Engine Protection Operating Mode.
3. The engine coolant temperature indicator lamp, if equipped, will illuminate.
4. The driver information center (DIC), if equipped, may display a message.
5. If the protection mode is active and an ECT sensor DTC sets, the protection mode will activate during the next drive cycle until the ECT sensor DTC runs and passes.

Conditions for Clearing the DTC

DTC P1258 is a Type A DTC.

1. Test the thermostat for correct operation. Refer to «Thermostat Diagnosis»(ref-364492-S33736182132010063000000) .
2. Test the engine cooling system for overheating. Refer to «Engine Overheating»(ref-364492-S26702970322010063000000) .
3. Inspect the water pump and coolant flow for correct operation. Refer to «Water Pump Replacement»(ref-364492-S21011260802010063000000) .
4. Inspect the engine for worn/leaking/cracked cylinder heads and engine block. Refer to «Coolant in Combustion Chamber»(ref-364568-S35418453842010063000000) and «Coolant in Engine Oil»(ref-364568-S02795382552010063000000) .

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following

1. Perform «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) and verify all of the following items: Ensure that the engine control module (ECM) and indicator lamp are operating correctly. Ensure that there are no diagnostic trouble codes (DTCs) that are stored. Scan tool data is within a normal operating range. Refer to «Control Module References»(ref-364489-S22329914082010063000000) for scan tool information.
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 system operation in order to familiarize yourself with the system functions. Refer to Cooling Fan Description and Operation (Gas) .

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 areas

1. Ensure that the control module grounds are clean, tight, and correctly located.
2. Inspect cooling system hoses and pipes for splits, kinks, and proper connections. Inspect thoroughly for any type of a leak or a restriction.
3. Inspect for a dirty or restricted radiator and 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 surge tank reservoir for the 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 (without HP2)»(ref-364492-S35763464092010063000000) or «Cooling Fan Always On (with HP2)»(ref-364492-S17895282172010063000000)
2. «Cooling Fan Inoperative (without HP2)»(ref-364492-S20987652682010063000000) or «Cooling Fan Inoperative (with HP2)»(ref-364492-S19487388372010063000000)
3. «Engine Overheating»(ref-364492-S26702970322010063000000)
4. «Loss of Coolant»(ref-364492-S09131545502010063000000)
5. «Thermostat Diagnosis»(ref-364492-S33736182132010063000000)
6. «Coolant Heater Inoperative»(ref-364492-S21556956552010063000000)
7. «Engine Fails To Reach Normal Operating Temperature»(ref-364492-S09731363992010063000000)

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The ECM has the capability of providing command to the fan relays even while 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.

1. Ignition OFF, disconnect each cooling fan relay one at a time.
2. Ignition ON, observe that the fans are not activated. If the fans are activated, test for a short to voltage in the relay controlled output circuit. If the fans are not activated, test or replace the appropriate cooling fan relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The ECM has the capability of providing command to the fan relays even while 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.

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(ref-364587-S39823871272010063000000) .
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-364486-S07394808542010063000000) for DTC P254F.
3. Ignition OFF, disconnect each cooling fan relay one at a time.
4. Ignition ON, observe that the fans are not activated. If the fans are activated, test for a short to voltage in the relay controlled output circuit. If the fans are not activated, test or replace the appropriate cooling fan relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 50-90 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Fan Low Relay

Fan Control Relay

Fan High Relay

1. The ECM has the capability of providing command to the fan relays even while 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: Fan Relay 1 operates both fans at a low speed Fan Relay 2 and 3 operates one fan at high speed Fan Relay 1, 2, and 3 operates both fans at high speed

Note. You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the cooling fan relays.
2. Connect a 30 A fused jumper between the Fan Control relay switch circuit terminal 30 and the relay ground circuit terminal 87. This will complete the left side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
3. Ignition ON, verify that a test lamp illuminates between ground and the relay switched ignition circuit terminal listed below: Fan Low Relay terminal 30 Fan High Relay terminal 30 If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate G10 cooling fan.
4. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below: Fan High Relay terminals 87 and 30 Fan Low Relay terminals 87 and 30 Verify the appropriate fan is activated. If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, test or replace the appropriate G10 cooling fan. If the corresponding cooling fan activates, replace the appropriate cooling fan relay.
5. Install the Fan Control Relay. Verify both fans activate at low speed. If both fans do not activate, test the Fan Control Relay switched output circuit terminal 87A for a short to ground or an open/high resistance.
6. If all the circuits test normal, test or replace the Fan Control Relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

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: Fan Relay 1 operates both fans at a low speed Fan Relay 2 operates both fans at medium speed Fan Relays 1, 2, and 3 operates both fans at high speed

Note. You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(ref-364587-S39823871272010063000000) .
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-364486-S07394808542010063000000) for DTC P254F.
3. Ignition OFF, disconnect the cooling fan relays.
4. Ignition ON, verify that a test lamp illuminates between the Fan Control relay ground circuit terminal 87 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
5. Connect a 30 A fused jumper between the Fan Control relay switch circuit terminal 30 and the relay ground circuit terminal 87. This will complete the left side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
6. Ignition ON, verify that a test lamp illuminates between ground and the relay switched ignition circuit terminal listed below: Fan Low Relay terminal 87 Fan Mid 1 Relay terminal 87 Fan Mid 2 Relay terminal 30 Fan High Relay terminal 30 If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate G10 cooling fan.
7. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below: Fan High Relay terminals 87 and 30 Fan Low Relay terminals 87 and 30 Verify the appropriate fan is activated. If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, test or replace the appropriate G10 cooling fan.
8. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below: Fan Mid 1 Relay terminal 87 and 30 Fan Mid 2 Relay terminal 30 and 87 The appropriate fan should activate and operate at a reduced speed. If the corresponding cooling fan does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the appropriate R10 cooling fan resistor. If the corresponding cooling fan activates, replace the appropriate cooling fan relay.
9. Ignition OFF, install the Fan Control relay.
10. Ignition ON, connect a 30 A fused jumper wire between the Fan Low relay terminals 87 and 30. Both cooling fans should activate and operate at a low speed. If both fans do not activate, test the Fan Control Relay switched output circuit terminal 87A for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the Fan Control relay.
11. If all the circuits test normal, test or replace the appropriate cooling fan relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 50-90 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the cooling fan relay.

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. Temperature sticks can be used to determine a thermostat's operating range, by rubbing 87°C (188°F) and 97°C (206°F) sticks on the thermostat housing.

1. Use a J 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.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Note. The power supply cord will test open due to an internal thermal switch if the ambient temperature is warmer than -10°C (14°F). The thermal switch is designed to close when the ambient temperature is below -18°C (0°F).

1. Test the engine coolant heater for an open or short to ground. If open or shorted, replace the heater.
2. If the heater tests normal, replace the coolant heater power cord.

Pressure Cap Testing

Special Tools

1. J 42401 Radiator Cap/Surge Tank Test Adapter. See «Special Tools»(ref-364492-S13195046632010063000000) .
2. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(ref-364492-S13195046632010063000000) .

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the J 24460-01 (1) with J 42401 (2) in order to test the pressure cap. See «Special Tools»(ref-364492-S13195046632010063000000) .
4. Test the pressure cap for the following conditions: Pressure release when the J 24460-01 exceeds the pressure rating of the pressure cap. See «Special Tools»(ref-364492-S13195046632010063000000) . 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

Special Tools

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(ref-364492-S13195046632010063000000) .
2. J 42401 Radiator Cap/ Surge Tank Test Adapter. See «Special Tools»(ref-364492-S13195046632010063000000) .

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(ref-364492-S05467308142010063000000) .
3. Wash the pressure cap mating surface with water.
4. Use the J 24460-01 with the J 42401 in order to apply pressure to the cooling system. See «Special Tools»(ref-364492-S13195046632010063000000) . 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.