Cooling Fan Control System Inspection
COOLING FAN SYSTEM INSPECTION
| Engine condition | Cooling fan relay | Cooling fan | ||
|---|---|---|---|---|
| No.1 | No.2 | |||
| ECT: 100 °C {212 °F} or less | OFF | OFF | Stop | |
| ECT: 100 °C {212 °F} or more (until 97 °C {207 °F} or less ) | ON | OFF | Low speed | |
| ECT: 108 °C {226 °F} or more (until 105 °C {221 °F} ) | ON | ON | High speed | |
| A/C and fan switches are on | Refrigerant pressure switch (middle pressure) OFF | ON | OFF | Low speed |
| Refrigerant pressure switch (middle pressure) ON | ON | ON | High speed | |
| ECT sensor malfunction | ON | ON | High speed | |
- Connect the M-MDS to the DLC-2.
- Perform the KOEO or KOER self test and verify that DTCs P0117:00, P0118:00, P0480:00 and/or P0481:00 are not shown using the KOEO and/or KOER self test. (See
KOEO/KOER SELF TEST [MZR 1.5]
).
- If DTCs P0117:00, P0118:00, P0480:00 and/or P0481:00 are shown, perform the applicable DTC troubleshooting procedure. (See DTC P0117:00 [MZR 1.5] ). (See DTC P0118:00 [MZR 1.5] ). (See DTC P0480:00 [MZR 1.5] ). (See DTC P0481:00 [MZR 1.5] ).
- Start the engine and let it at idle with ECT below 100 °C {212 °F} .
- Verify that the cooling fan is not operating when A/C switch and fan switch are turned off.
- If the cooling fan is operating, inspect for the following based on cooling fan status:
Cooling fan status Inspection item Low speed - Cooling fan relay No.1 (stuck close)
- Cooling fan relay No.2 (stuck close)
- Wiring harness between refrigerant pressure switch (low, high) and PCM terminal 1AO(1) (short to ground) (PCM PID AC_REQ is always ON)
- Wiring harness between cooling fan relay No.1 and cooling fan (short to power supply)
- Wiring harness between cooling fan relay No.2 and cooling fan (short to power supply)
High speed - Wiring harness between refrigerant pressure switch (low, high) and PCM terminal 1AO(2) (short to ground) (PCM PID AC_REQ is always ON)
(1) While refrigerant pressure switch (middle) is OFF (2) While refrigerant pressure switch (middle) is ON - Using the M-MDS simulation function, turn FAN1 from the off position to the ON position, and verify that cooling fan operates at low speed.
- If the operation could not be confirmed, inspect for the following based on cooling fan status:
Cooling fan status Inspection item Stop - Cooling fan relay No.1 (stuck open)
- Cooling fan (internal circuit open)
- Wiring harness in battery-cooling fan relay No. 1-cooling fan (open circuit, fuse is melted by short to ground)
- Wiring harness in cooling fan-body ground (open circuit)
- Poor contact of cooling fan ground point
High speed - Cooling fan (internal circuit short)
- Wiring harness of cooling fan power supply circuit (from cooling fan No.1 and from cooling fan relay No.2) (short to each other)
- Using the M-MDS simulation function, turn FAN1 and FAN2 from the off position to the ON position, and verify that cooling fan operates at high speed.
- If the operation could not be confirmed, inspect for the following based on cooling fan status:
Cooling fan status Inspection item Low speed - Cooling fan relay (stuck open)
- Cooling fan (internal circuit open)
- Wiring harness between battery positive terminal and cooling fan relay (open circuit, fuse is melted by short to ground)
- Wiring harness between cooling fan terminal A and body ground (open circuit)
- Wiring harness between cooling fan terminal B and body ground (open circuit)