Cooling fan system operation (at idle)
COOLING FAN SYSTEM OPERATION
| Engine condition | Fan relay No.1 | Fan relay No.2 | Fan relay No.3 | Fan relay No.4 | Cooling fan motor No.1 | Cooling fan motor No.2 | |
|---|---|---|---|---|---|---|---|
| Engine coolant temperature below 100°C {212°F} | OFF | OFF | OFF | OFF | OFF | OFF | |
| Engine coolant temperature above 100°C {212°F} (until 97°C {208°F}) | ON | OFF | OFF | ON | Low speed | Low speed | |
| Engine coolant temperature above 108°C {233°F} (until 105°C {221°F}) | ON | ON | ON | ON | High speed | High speed | |
| A/C and fan switches are on. | Refrigerant pressure switch (middle pressure) is off. | ON | OFF | OFF | ON | Low speed | Low speed |
| Refrigerant pressure switch (middle pressure) is on. | ON | ON | ON | OFF | High speed | Middle speed | |
| ECT sensor malfunction | ON | ON | ON | ON | High speed | High speed | |
- Connect M-MDS to DLC-2.
- Verify that DTC P0480, P0481, and P0482 are not displayed.
- If DTC P0480, P0481 or P0482 are displayed, perform DTC inspection.
- Verify that ECT PID is below cooling fan operating temperature.
- Verify that the A/C switch and fan switch are off.
- Start the engine and idle it.
- Verify that the cooling fans are not operating.
- If cooling fan No.1 is operating, inspect whether cooling fan relay No.2 is stuck in the closed position.
- If the cooling fans are operating, inspect whether cooling fan relay No.1 is stuck in the closed position.
- If the cooling fans are operating at high speed, inspect DTC for ECT sensor (P0117, P0118).
- If cooling fan No.1 does not operate and cooling fan No.2 is operating, inspect whether cooling fan relay No.3 is stuck in the closed.
- Start the engine.
- Verify that the cooling fans are low speed when ECT PID is 100°C {212°F} or above
.
- If cooling fan No.1 does not operate, verify that DTC P0480 is not detected.
- If DTC P0480 is detected, perform DTC inspection.
- If DTC P0480 is not detected, inspect for the following:
- Cooling fan relay No.2 is stuck in open position.
- Open circuit in wiring harnesses or connectors or both between cooling fan relay No.2 and cooling fan motor No.1.
- If the cooling fan No.2 does not operate, verify that DTC P0482 is not detected.
- If DTC P0482 is detected, perform DTC inspection.
- If DTC P0482 is not detected, inspect the following:
- Cooling fan relay No.3 is stuck in open position.
- Open circuit in wiring harnesses or connectors or both between cooling fan relay No.3 and cooling fan motor No.2
- If cooling fan No.1 or cooling fan No.2 or both are operating at high speed, verify that DTC P0481 is not detected.
- If DTC P0481 is detected, perform DTC inspection.
- If DTC P0481 is not detected, inspect the following:
- Cooling fan relay No.1 is stuck in closed position.
- Cooling fan relay No.4 is stuck in closed position.
- If cooling fan No.1 does not operate, verify that DTC P0480 is not detected.
- Turn A/C switch and fan switch on.
- Verify that A/C is operating.
- If A/C is not operating, inspect the following:
- A/C switch
- Fan switch
- Refrigerant pressure switch
- If A/C is not operating, inspect the following:
- Verify that cooling fan No.1 is operating at high speed and cooling fan No.2 is operating other than at low speed (high or middle speed).
- If the cooling fan relay does not operate high speed and cooling fan No.2 is operating low speed, inspect the following:
- Cooling fan relay No.1 is stuck in open position.
- Cooling fan relay No.4 is stuck in open position.
- If the cooling fan relay does not operate high speed and cooling fan No.2 is operating low speed, inspect the following: