Mazda 6 2002, Workshop Manual

Page: 367 / 1248

TROUBLESHOOTING
F–237
F
L8, LF (Intensely hot area) engine models
Cooling fan system operation (at idle)
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.
Engine condition
Cooling fan
relay No.2
Cooling fan
relay No.4
Cooling fan
relay No.1
Cooling fan
relay No.3
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 below 97
°
C
{208
°
F})
ON OFF OFF OFF Low speed OFF
Engine coolant temperature above
108
°
C {233
°
F} (until below 105
°
C
{208
°
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 OFF
Refrigerant pressure
switch (middle
pressure) is on.
ON ON ON OFF High speed Low speed
ECT sensor malfunction ON ON ON ON High speed High speed