Mazda 2002 6 Workshop Manual page 367

L8, LF (Intensely hot area) engine models
Cooling fan system operation (at idle)
Engine condition
Engine coolant temperature below
100°C {212°F}
Engine coolant temperature above
100°C {212°F} (until below 97°C
{208°F})
Engine coolant temperature above
108°C {233°F} (until below 105°C
{208°F})
Refrigerant pressure
switch (middle
A/C and fan
pressure) is off.
switches are
Refrigerant pressure
on.
switch (middle
pressure) is on.
ECT sensor malfunction
1. Connect WDS or equivalent to DLC-2.
2. Verify that ECT PID is below cooling fan operating temperature.
3. Verify that the A/C switch and fan switch are off.
4. Start the engine and let it at idle.
5. Verify that the cooling fans fan are not operating.
• If the cooling fan is operating low speed, inspect for following:
— Short to GND circuit between PCM terminal 4L and cooling fan relay No.2
— Cooling fan relay No.2 stuck in closed position
• If the cooling fans are operating high speed, inspect for following:
— DTC for ECT sensor (P0117, P0118)
• If the cooling fan motor No.1 is not operating and cooling fan motor No.2 is operating, inspect for following:
— Short to GND circuit between PCM terminal 4F and cooling fan relay No.1
— Cooling fan relay No.1 stuck ON
— Short to GND circuit between PCM terminal 4B and cooling fan relay No.3
— Cooling fan relay No.3 stuck ON
6. Start the engine.
7. Verify that the cooling fans are operating low speed when ECT PID is above 100°C {212°F}.
• If the cooling fan motor No.1 does not operate, perform the following:
1. Select FAN3 PID.
2. Operate cooling fan relay No.2 by sending ON command.
3. Inspect the operation sound is heard from cooling fan relay No.2.
— If the operation sound is heard, inspect wiring harnesses, connectors and cooling fan motor No.1.
— If the operation sound is not heard, inspect cooling fan relay No.2 and open circuit between PCM
terminal 4L and cooling fan relay No.2 wiring harness and connectors.
• Inspect the cooling fan is operating high speed, inspect the following:
— Short to GND circuit between PCM terminal 4F and cooling fan relay No.1/cooling fan relay No.4.
8. Turn A/C switch and fan switch are on.
9. Verify that the ACCS PID is ON.
• If the ACCS PID is not ON, inspect for following:
— A/C switch
— Fan switch
— Refrigerant pressure switch
— Open circuit PCM 1AC related harnesses and connectors
10. Access the COLP PID.
11. Verify that the cooling fan motor No.1 is operating high speed and cooling fan motor No.2 is operating low
speed, while the COLP PID is ON.
• If the cooling fan motor No.1 does not operate high speed, perform the following:
1. Select FAN1 PID.
2. Operate cooling fan relay No.1 and cooling fan relay No.4 by sending ON command.
TROUBLESHOOTING
Cooling fan Cooling fan
relay No.2 relay No.4
OFF OFF
ON OFF
ON ON
ON OFF
ON ON
ON ON
Cooling fan Cooling fan
relay No.1 relay No.3
OFF OFF
OFF OFF
ON ON
OFF ON
ON OFF
ON ON
Cooling fan Cooling fan
motor No.1 motor No.2
OFF OFF
Low speed OFF
High speed High speed
Low speed OFF
High speed Low speed
High speed High speed
F–237
F