Engine Cooling System: Diagnosis Subaru BRZ ZC

Symptom Table

COOLING FAN SYSTEM

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Circuit description

For the cooling fan, the engine control computer turns ON/OFF the cooling fan relay using the engine coolant temperature, A/C switch, A/C refrigerant pressure, engine speed and vehicle speed signals.

To control the cooling fan motor speed in two stages, the engine control computer turns ON/OFF the fan relay to switch between the series and parallel connections of cooling fan motor circuit.

Inspection steps

Note. Read the freeze frame data using the SSM3. In the freeze frame data, part of the engine running condition at a trouble occurrence is stored and these information is helpful for troubleshooting.

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1. FAN NO. 1 relay check (power supply voltage) Remove the FAN NO. 1 relay from the engine compartment relay block. Measure the voltage between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. VOLTAGE Inspection terminals Inspection conditions Standard value 5 (FAN NO. 1) - chassis ground Always 11 to 14V NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
2. FAN NO. 3 relay check (power supply voltage) Remove the FAN NO. 3 relay from the engine compartment relay block. Measure the voltage between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. VOLTAGE Inspection terminals Inspection conditions Standard value 5 (FAN NO. 3) - chassis ground Always 11 to 14V NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
3. Engine compartment relay block check (power supply voltage) Remove the FAN NO. 1 relay, FAN NO. 2 relay and FAN NO. 3 relay from the engine compartment relay block. Turn the ignition switch to ON. Measure the voltage between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. Inspection terminals Inspection conditions Standard value 2 (FAN NO. 1) - chassis ground IG ON 11 to 14V 1 (FAN NO. 2) - chassis ground IG ON 11 to 14V 2 (FAN NO. 3) - chassis ground IG ON 11 to 14V NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
4. FAN NO. 1 relay unit inspection Remove the FAN NO. 1 relay from the engine compartment relay block. Measure the resistance between the terminals. RESISTANCE Inspection terminals Inspection conditions Standard value 3 - 5 When the battery voltage is not applied to the terminals 1 and 2: 10 k ohmsor more 3 - 5 When the battery voltage is applied to the terminals 1 and 2: Less than 1 ohms NG: FAN NO. 1 relay replacement OK: Go to Next Step
5. FAN NO. 2 relay unit inspection Remove the FAN NO. 2 relay from the engine compartment relay block. Measure the resistance between the terminals. RESISTANCE Inspection terminals Inspection conditions Standard value 3 - 4 When the battery voltage is not applied to the terminals 1 and 2: Less than 1 ohms 3 - 4 When the battery voltage is applied to the terminals 1 and 2: 10 k ohmsor more 3 - 5 When the battery voltage is not applied to the terminals 1 and 2: 10 k ohmsor more 3 - 5 When the battery voltage is applied to the terminals 1 and 2: Less than 1 ohms NG: FAN NO. 2 relay replacement OK: Go to Next Step
6. FAN NO. 3 relay unit inspection Remove the FAN NO. 3 relay from the engine compartment relay block. Measure the resistance between the terminals. RESISTANCE Inspection terminals Inspection conditions Standard value 3 - 5 When the battery voltage is not applied to the terminals 1 and 2: 10 k ohmsor more 3 - 5 When the battery voltage is applied to the terminals 1 and 2: Less than 1 ohms NG: FAN NO. 3 relay replacement OK: Go to Next Step
7. Check wiring harness and connector (FAN NO. 2 relay - chassis ground) NOTE: For the inspection procedure and precautions for wiring harnesses and connectors, refer to «INSPECTION PROCEDURES FOR ELECTRICAL CIRCUITS AND HOW TO PERFORM»(ref-619149-S21627727182014053000000) . Remove the FAN NO. 2 relay from the engine compartment relay block. Measure the resistance between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. RESISTANCE Inspection terminals Inspection conditions Standard value 5 (FAN NO. 2) - chassis ground Always Less than 1 ohms NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
8. Cooling fan motor check Disconnect the cooling fan motor connector. Connect the battery positive (+) terminal to the terminal 1 of cooling fan motor connector and the negative (-) terminal to the terminal 2. Check the cooling fan for rotation. Result: Rotates NG: Cooling fan motor replacement (Refer to «REMOVAL»(ref-619192-S15296362252014053000000) ) OK: Go to Next Step
9. Check wiring harness and connector (Cooling fan motor - Chassis ground) NOTE: For the inspection procedure and precautions for wiring harnesses and connectors, refer to «INSPECTION PROCEDURES FOR ELECTRICAL CIRCUITS AND HOW TO PERFORM»(ref-619149-S21627727182014053000000) . Disconnect the connector A45 of cooling fan motor. Measure the resistance between the terminals. RESISTANCE Inspection terminals Inspection conditions Standard value A45-1 - Chassis ground Always Less than 1 ohms NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
10. Check wiring harness and connector (cooling fan motor - engine compartment relay block) NOTE: For the inspection procedure and precautions for wiring harnesses and connectors, refer to «INSPECTION PROCEDURES FOR ELECTRICAL CIRCUITS AND HOW TO PERFORM»(ref-619149-S21627727182014053000000) . Disconnect the connector A45 of cooling fan motor. Remove the FAN NO. 1 relay and FAN NO. 2 relay from the engine compartment relay block. Measure the resistance between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. RESISTANCE (OPEN CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value A45-2 - 3 (FAN NO. 1 relay) Always Less than 1 ohms A45-2 - 4 (FAN NO. 2 relay) Always Less than 1 ohms RESISTANCE (SHORT CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value A45-2 and 3 (FAN NO. 1 relay) - other terminals and chassis ground Always 10 k ohmsor more A45-2 and 4 (FAN NO. 2 relay) - other terminals and chassis ground Always 10 k ohmsor more NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
11. Cooling fan motor NO. 2 check Disconnect the cooling fan motor NO. 2 connector. Connect the battery positive (+) terminal to the terminal 1 of cooling fan motor NO. 2 connector and the negative (-) terminal to the terminal 2. Check the cooling fan for rotation. Result: Rotates NG: Cooling fan motor NO. 2 replacement (Refer to «REMOVAL»(ref-619192-S15296362252014053000000) ) OK: Go to Next Step
12. Check wiring harness and connector (cooling fan motor NO. 2 - engine compartment relay block) NOTE: For the inspection procedure and precautions for wiring harnesses and connectors, refer to «INSPECTION PROCEDURES FOR ELECTRICAL CIRCUITS AND HOW TO PERFORM»(ref-619149-S21627727182014053000000) . Disconnect the cooling fan motor NO. 2 connector A46. Remove the FAN NO. 2 relay and FAN NO. 3 relay from the engine compartment relay block. Measure the resistance between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. RESISTANCE (OPEN CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value A46-1 - 3 (FAN NO. 2 relay) Always Less than 1 ohms A46-2 - 3 (FAN NO. 3 relay) Always Less than 1 ohms RESISTANCE (SHORT CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value A46-1 and 3 (FAN NO. 2 relay) - other terminals and chassis ground Always 10 k ohmsor more A46-2 and 3 (FAN NO. 3 relay) - other terminals and chassis ground Always 10 k ohmsor more NG: Repair or replacement of wiring harness or connector OK: Go to Next Step
13. Engine compartment relay block check Remove the FAN NO. 1 relay and FAN NO. 2 relay from the engine compartment relay block. Measure the resistance between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. RESISTANCE (OPEN CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value 1 (FAN NO. 1 relay) - 2 (FAN NO. 2 relay) Always Less than 1 ohms RESISTANCE (SHORT CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value 1 (FAN NO. 1 relay) and 2 (FAN NO. 2 relay) - other terminals and chassis ground Always 10 k ohmsor more NG: Engine compartment relay block replacement OK: Go to Next Step
14. Check wiring harness and connector (engine control computer - engine compartment relay block) NOTE: For the inspection procedure and precautions for wiring harnesses and connectors, refer to «INSPECTION PROCEDURES FOR ELECTRICAL CIRCUITS AND HOW TO PERFORM»(ref-619149-S21627727182014053000000) . Disconnect the connector A35 of engine control computer. Remove the FAN NO. 2 relay and FAN NO. 3 relay from the engine compartment relay block. Measure the resistance between the terminals. CAUTION: When measuring the voltage by putting the tester probe etc. on the holder, the holder may be damaged if the probe is pressed against the holder too strong. RESISTANCE (OPEN CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value A35-11 (FAN1) - 1 (FAN NO. 1 relay) Always Less than 1 ohms A35-11 (FAN1) - 2 (FAN NO. 2 relay) Always Less than 1 ohms A35-12 (FAN2) - 1 (FAN NO. 3 relay) Always Less than 1 ohms RESISTANCE (SHORT CIRCUIT CHECK) Inspection terminals Inspection conditions Standard value A35-11 (FAN1) and 1 (FAN NO. 1 relay) - other terminals and chassis ground Always 10 k ohmsor more A35-11 (FAN1) and 2 (FAN NO. 2 relay) - other terminals and chassis ground Always 10 k ohmsor more A35-12 (FAN2) and 1 (FAN NO. 3 relay) - other terminals and chassis ground Always 10 k ohmsor more NG: Repair or replacement of wiring harness or connector OK: Replacement of the engine control computer (Refer to «INSTALLATION»(ref-619157-S05637487422014053000000) )

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1. Coolant (SUBARU Super Coolant) draining WARNING: To avoid the risk of burn, do not remove the radiator cap sub-assembly when the engine and radiator are hot. The fluid and steam may blow out due to the pressure. Remove the service hole cover of front bumper under cover. Connect the hose with an inner diameter of ø8 mm {0.315 in} to the drain plug. Loosen the radiator drain cock plug. Remove the radiator cap sub-assembly and drain the coolant.
2. Coolant (SUBARU Super Coolant) refill NOTE: Turn the A/C switch to OFF before refilling the coolant. Tighten the radiator drain cock plug. Fill the cooling system conditioner into the water inlet filler. Fill the coolant of the specified concentration into the water inlet filler neck up to the filler neck position. NOTE: The SUBARU Super Coolant contains anti-freeze and anti-rust agents for the engines with an aluminum cylinder block. Be sure to use the SUBARU Super Coolant, since the use of undesignated coolant may cause corrosion. Press the radiator hose No. 1 and radiator outlet hose several times and add the coolant if the level at the water inlet filler neck drops. Open the air bleeding plug on the heater hose side. If the level at the water inlet filler neck drops, fill the coolant into the radiator filler neck up to the filler neck position. Close the air bleeder valve when the coolant comes out from the air bleeder plug on the heater hose side. Fill the coolant of the specified concentration up to the FULL level of radiator reservoir tank. Tighten the radiator cap.[*1] Start the engine. Race 5 to 6 times at 3, 000 rpm or less and then stop the engine.[*2] NOTE: Complete this operation within 40 seconds. After about 1 minute, remove the radiator cap, open the air bleeding plug of heater hose side and fill the coolant if the level at the water inlet filler neck is low, and then close the air bleeding plug. [*3] Repeat the steps [* 1 ], [* 2 ] and [* 3 ] until the level at the water inlet filler neck does not drop. NOTE: When the engine warms up and the thermostat valve opens, the air from the radiator hose No. 1 enters into the radiator side. Therefore, complete the steps before the engine warms up. Tighten the radiator cap and radiator reservoir tank cap. Start the engine and operate the heater at maximum hot position and the blower speed setting to "LO". Run the engine at 2, 000 rpm or less until the radiator fan starts and stops.[*4] NOTE: Be careful with the engine coolant temperature to prevent overheating. Stop the engine and wait until the coolant temperature lowers to 30°C (86°F) or less.[*5] Remove the radiator cap, and if the coolant level drops, fill the coolant into the radiator up to the filler neck position and the radiator reservoir tank up to its FULL level.[*6] Tighten the radiator cap.[*7] Set the heater setting to maximum hot position and the blower speed setting to LO and start the engine. Perform racing at 3, 000 rpm or less.[*8] If the flowing sound of engine coolant is heard from the heater core at this time, perform the steps [*4], [*5], [*6], [*7] and[*8] again. When the level does not drop any more, adjust the level of radiator reservoir tank to the FULL line.
3. Leak check of coolant (SUBARU Super Coolant) (Refer to «ON-VEHICLE INSPECTION»(ref-619192-S42694459552014053000000) )