DTC Diagnosis Procedure
The blower motor utilizes a brush-less motor with a rotating magnet. Quietness is improved over previous motors where the brush was the point of contact and the coil rotated.
Battery voltage is supplied to the front blower motor from fuses (Nos. 10 and 18) located in the fuse block (J/B). The voltage is controlled through two relays which are energized whenever the ignition switch is in the ON or START position.
Fan speed is modified by controlling the ground circuit. A power transistor is integrated into the ground side of the front blower fan circuit. The front air control provides voltage to the gate of the power transistor based on the position of the blower control dial. By applying a variable voltage to the gate, the power transistor controls the current flow to ground, thereby controlling the speed of the blower motor. The front air control monitors the blower motor ground circuit. This allows the front air control to minutely adjust the voltage supplied to the gate to smooth out any power surges. The blower control dial has 26 detents, each detent outputting a different gate voltage to the power transistor, allowing for 26 different fan speeds. The mode selection also affects fan speed. Refer to Air Flow Control .
- CHECK FUSES
- Turn ignition switch OFF.
- Check 15 A fuses [Nos. 10 and 18, located in fuse block (J/B)].NOTE: Refer to appropriate system Wiring Diagram.
Is the inspection result normal?
YES
GO TO 2.
NO
Replace the blown fuse after repairing the affected circuit.
- CHECK FRONT BLOWER MOTOR POWER SUPPLY
- Disconnect front blower motor connector.
- Turn ignition switch ON.
- Check voltage between front blower motor harness connector and ground.
+
-
Voltage
(Approx.)
Front blower motor
Connector
Terminal
M62
1
Ground
Battery voltage
Is the inspection result normal?
YES
GO TO 3.
NO
GO TO 8.
- CHECK FRONT BLOWER MOTOR GROUND CIRCUIT
- Turn blower control dial fully counterclockwise to the OFF position
- While turning the blower control dial clockwise, through each detent, check the resistance between front blower motor harness connector and ground.
Front blower motor
--
Continuity
Connector
Terminal
M62
2
Ground
Decreases as dial approaches full speed
Is the inspection result normal?
YES
GO TO 11.
NO
GO TO 4
- CHECK FRONT BLOWER MOTOR GROUND CIRCUIT CONTINUITY
- Disconnect power transistor connector.
- Check continuity between front blower motor harness connector and power transistor connector.
Front blower motor
Power transistor
Continuity
Connector
Terminal
Connector
Terminal
M62
2
M52
3
Yes
Is the inspection result normal?
YES
GO TO 5.
NO
Repair the harness or connector.
- CHECK POWER TRANSISTOR CONTROL SIGNAL CIRCUIT
- Turn blower control dial fully counterclockwise to the OFF position
- While turning the blower control dial clockwise, through each detent, check voltage between power transistor and ground.
Power transistor
Condition
Connector
Terminal
Blower control dial detents
MAX A/C, VENT, and B/L
FOOT, D/F0
D/F1, DEF
P/REC Mode
Voltage
M52
2
Ground
OFF
0.00 volts
0.00 volts
0.00 volts
0.00 volts
1
3.25 volts
3.75 volts
3.75 volts
3.75 volts
2
3.50 volts
4.00 volts
4.00 volts
4.00 volts
3
3.75 volts
4.25 volts
4.25 volts
4.25 volts
4
4.00 volts
4.50 volts
4.50 volts
4.50 volts
5
4.50 volts
4.75 volts
4.75 volts
4.75 volts
6
4.75 volts
5.00 volts
5.00 volts
5.00 volts
7
5.00 volts
5.50 volts
5.50 volts
5.50 volts
8
5.25 volts
5.75 volts
5.75 volts
5.75 volts
9
5.50 volts
6.00 volts
6.00 volts
6.00 volts
10
5.75 volts
6.25 volts
6.25 volts
6.25 volts
11
6.25 volts
6.50 volts
6.50 volts
6.50 volts
12
6.50 volts
6.75 volts
6.75 volts
6.75 volts
13
6.75 volts
7.00 volts
7.00 volts
7.00 volts
14
7.00 volts
7.25 volts
7.25 volts
7.25 volts
15
7.50 volts
7.50 volts
7.50 volts
7.50 volts
16
7.75 volts
7.75 volts
7.75 volts
7.75 volts
17
8.00 volts
8.00 volts
8.25 volts
8.00 volts
18
8.25 volts
8.25 volts
8.50 volts
8.25 volts
19
8.50 volts
8.50 volts
8.75 volts
8.50 volts
20
8.75 volts
8.75 volts
9.00 volts
8.75 volts
21
9.00 volts
9.00 volts
9.25 volts
9.00 volts
22
9.25 volts
9.25 volts
9.50 volts
9.25 volts
23
9.75 volts
9.75 volts
10.00 volts
9.50 volts
24
10.25 volts
10.25 volts
10.25 volts
10.75 volts
25
10.50 volts
10.50 volts
10.50 volts
10.00 volts
26
10.75 volts
10.75 volts
12.00 volts
10.25 volts
12 = Max blower voltage
Is the inspection result normal?
YES
GO TO 6.
NO
GO TO 7.
- CHECK POWER TRANSISTOR GROUND CIRCUIT
Check continuity between power transistor connector and ground.
Power transistor
--
Continuity
Connector
Terminal
M52
1
Ground
Yes
Is the inspection result normal?
YES
Replace power transistor. Refer to Removal and Installation .
NO
Repair harness or connector.
- CHECK POWER TRANSISTOR CONTROL SIGNAL CIRCUIT CONTINUITY
- Disconnect front air control connector.
- Check continuity between power transistor connector and front air control connector.
Power transistor
Front air control
Continuity
Connector
Terminal
Connector
Terminal
M52
2
M49
14
Yes
Is the inspection result normal?
YES
Replace front air control. Refer to Removal and Installation - Front Air Control .
NO
Repair the harness or connector.
- CHECK FRONT BLOWER MOTOR RELAY GROUND CIRCUIT
Check continuity between fuse block (J/B) harness connector and front blower motor relay-2 connector and ground.
Component
--
Continuity
Connector
Terminal
Fuse block (J/B) M3
7N
Ground
Yes
Front blower motor relay-2 M60
2
Is the inspection result normal?
YES
GO TO 9.
NO
Repair harness or connector.
- CHECK FRONT BLOWER MOTOR RELAYS
Check front blower motor relay-1 and front blower motor relay-2. Refer to Component Inspection (Front Blower Motor Relay) .
Is the inspection result normal?
YES
GO TO 10.
NO
Replace inoperative front blower motor relay.
- CHECK FUSE BOX (J/B)
Check voltage between fuse block (J/B) connector and ground.
Fuse block (J/B)
Voltage
(Approx.)
Connector
Terminal
M3
8N
Ground
Battery voltage
M4
1P
Is the inspection result normal?
YES
Repair harness or connector between front blower motor and fuse block (J/B).
NO
Replace fuse block (J/B).
- CHECK FRONT BLOWER MOTOR
Check front blower motor. Refer to Component Inspection (Front Blower Motor) .
Is the inspection result normal?
YES
Check intermittent incident. Refer to Intermittent Incident .
NO
Replace front blower motor.