Blower Motor Does Not Operate
Possible Source(s):
Fuse(s).
Circuit.
Blower motor relay #1.
Blower motor.
Mode selector switch.
Blower motor resistor.
Action(s) to Take:
BM1: CHECK FUSES
Check the 15A ENGINE fuse in the interior fuse panel and the 40A HEATER fuse in the main fuse panel.
Are the fuses OK?
Yes
GO to BM4.
No
GO to BM2.
BM2: CHECK SYSTEM
Key OFF.
Replace the blown fuse(s).
Key ON.
Do any of the fuses fail again?
Yes
GO to BM3.
No
GO to BM4.
BM3: CHECK FOR SHORTS TO GROUND
Key OFF.
Disconnect the 10-pin interior fuse panel connector and remove the 40A HEATER fuse from the motor fuse panel.
Disconnect the blower motor relay #1 connector near the right front of the radiator.
Measure the resistance of the "BK/W" wire between the 10-pin interior fuse panel connector and ground.
Measure the resistance of the "BL" wire between the left terminal of the 40A HEATER fuse holder and ground.
Are any resistances less than 5 ohms?
Yes
SERVICE wire(s) in question.
No
RECONNECT the 10-pin interior fuse panel connector. REPLACE the 40A HEATER fuse and/or the 15A ENGINE fuse. RECONNECT the blower motor relay #1. GO to BM4.
BM4: CHECK VOLTAGE AT BLOWER MOTOR
Key OFF.
Disconnect the blower motor connector on the blower assembly.
Key ON.
Measure the voltage on the "R" wire at the blower motor connector.
Is the voltage greater than 10 volts?
Yes
GO to BM8.
No
GO to BM5.
BM5: CHECK POWER TO BLOWER MOTOR RELAY #1
Key OFF.
Disconnect the blower motor relay #1 connector near the right front of the radiator.
Key ON.
Measure the voltage on the "BK/W" wire and the "BL" wire at the blower motor relay #1 connector.
Are the voltages greater than 10 volts?
Yes
GO to BM6.
No
SERVICE the "BK/W" and/or "BL" wire(s).
BM6: CHECK BLOWER MOTOR RELAY #1
Key OFF.
Disconnect the blower motor relay #1 connector.
Measure the resistance between the "BL" and "W" wire terminals on the relay.
Apply 12 volts to the "BK/W" wire terminal and ground to the "BK/R" wire terminal on the relay.
Measure the resistance between the "BL" wire terminal and the "W" wire terminal on the relay.
Is the resistance less than 5 ohms when 12 volts and ground are applied, and greater than 10,000 ohms when 12 volts and ground are not applied?
Yes
GO to BM7.
No
REPLACE the blower motor relay #1.
BM7: CHECK BLOWER MOTOR RELAY #1 GROUND CIRCUIT
Key OFF.
Disconnect the blower motor relay #1 connector.
Measure the resistance of the "BK/R" wire between the blower motor relay #1 connector and ground.
Is the resistance less than 5 ohms?
Yes
SERVICE the "W" - "R" wire between the blower motor relay #1 and the blower motor.
No
SERVICE the "BK/R" wire between the blower motor relay #1 and the starter motor.
BM8: CHECK BLOWER MOTOR
Key OFF.
Disconnect the blower motor connector.
Apply 12 volts to the "R" wire terminal and ground to the "BL/O" wire terminal at the blower motor.
Does the motor operate at HI speed?
Yes
GO to BM9.
No
REPLACE the blower motor.
BM9: CHECK MODE SELECTOR SWITCH GROUND
Key OFF.
Disconnect the mode selector switch connector.
Measure the resistance of the "BK" wire (circuit 52) between the mode selector switch connector and ground.
Is the resistance less than 5 ohms?
Yes
GO to BM10.
No
SERVICE the "BK" wire.
BM10: CHECK MODE SELECTOR SWITCH
Key OFF.
Disconnect the mode selector switch connector.
Measure the resistance between the "BL/Y" terminal and the "BK" wire terminal (circuit 52) wire at the mode selector switch with the switch in the following positions:<pre>Mode Selector Switch Position Resistance (ohms)
OFF greater than 10,000 ohms
VENT less than 5 ohms
FLOOR less than 5 ohms
MIX less than 5 ohms
DEF less than 5 ohms
NORM A/C (If equipped) less than 5 ohms
MAX A/C (If equipped) less than 5 ohms</pre>Are the resistances as specified?
Yes
GO to BM11.
No
REPLACE the mode selector switch.
BM11: CHECK WIRE BETWEEN MODE SELECTOR SWITCH AND BLOWER MOTOR RESISTOR
Key OFF.
Disconnect the mode selector switch connector.
Disconnect the blower motor resistor connector on the blower assembly, the blower motor relay #2 connector and the blower switch connector.
Measure the resistance between the "BL/Y" wire at the mode selector switch connector and the "GN/R" wire at the blower motor resistor connector.
Measure the resistance of the "BL/Y" wire between the mode selector switch connector and ground.
Is the resistance less than 5 ohms between the mode selector switch connector and the blower motor resistor connector, and greater than 10,000 ohms between the mode selector switch connector and ground?
Yes
GO to BM12.
No
SERVICE the "BL/Y" - "GN/R" wire.
BM12: CHECK WIRE BETWEEN BLOWER MOTOR AND BLOWER MOTOR RESISTOR
Key OFF.
Disconnect the blower motor connector.
Disconnect the blower motor resistor connector on the blower assembly.
Disconnect the blower switch connector.
Measure the resistance between the "BL/O" wire at the blower motor connector and "BL/W" wire at blower motor resistor connector.
Measure the resistance of the "BL/O" wire between the blower motor connector and ground.
Is the resistance less than 5 ohms between the blower motor connector and the blower motor resistor connector, and greater than 10,000 ohms between the blower motor connector and ground?
Yes
GO to BM13.
No
SERVICE the "BL/O"-"BL/W" wire.
BM13: CHECK BLOWER MOTOR RESISTOR
Key OFF.
Disconnect the blower motor resistor connector on the blower assembly.
Measure the resistance between the terminals of the blower motor resistor as indicated:<pre> Terminals Resistance (ohms)
BL/W and GN/R 2.76 ohms
BL/W and BL 1.07 ohms
BL/W and R/BK 0.38 ohms</pre>Are the resistances approximately as indicated?
Yes
GO to BM14.
No
REPLACE the blower motor resistor.
BM14: CHECK BLOWER SWITCH
Key OFF.
Disconnect the blower switch connector.
Measure the resistance between the terminals of the blower switch as indicated:<pre>Switch Terminals Resistance (ohms)
Position
LO All greater than 10,000 ohms
2nd BL/Y and BL less than 5 ohms
All others greater than 10,000 ohms
3rd BL/Y and BL less than 5 ohms
BL/Y and BL/BK less than 5 ohms
BL and BL/BK less than 5 ohms
All others greater than 10,000 ohms
HI BL/Y and BL/BK less than 5 ohms
BL/Y and BL/W less than 5 ohms
BL/BK and BL/W less than 5 ohms
All others greater than 10,000 ohms</pre>Are the resistances as indicated?
Yes
GO to BM15.
No
REPLACE the blower switch.
BM15: CHECK WIRE BETWEEN BLOWER SWITCH AND MODE SELECTOR SWITCH
Key OFF.
Disconnect the blower switch connector and the mode selector switch connector.
Measure the resistance of the "BL/Y" wire between the blower switch connector and the mode selector switch connector.
Is the resistance less than 5 ohms?
Yes (Blower motor stays at LO speed in 2nd blower switch position)
SERVICE the "BL" wire between the blower switch and the blower motor resistor.
Yes (Blower motor stays at second speed in 3rd blower switch position)
GO to BM16.
Yes (Blower stays at third speed in HI blower switch position)
SERVICE the "BL/W" wire between the blower switch and the blower motor resistor.
No
SERVICE the "BL/Y" wire.
BM16: CHECK FUSE
Check the 15A METER fuse located in the interior fuse panel.
Is the fuse OK?
Yes
GO to BM19.
No
GO to BM17.
BM17: CHECK SYSTEM
Key OFF.
Replace the 15A METER fuse.
Key ON.
Does the fuse fail again?
Yes
GO to BM18.
No
GO to BM19.
BM18: CHECK FOR SHORTS TO GROUND
Key OFF.
Disconnect the 14-pin interior fuse panel connector.
Disconnect the blower motor relay #2 connector at the blower assembly.
Measure the resistance of the "BK/Y" wire between the 14-pin interior fuse panel connector and ground.
Is the resistance less than 5 ohms?
Yes
SERVICE the "BK/Y" wire.
No
REPLACE the 15A METER fuse. RECONNECT the 14-pin interior fuse panel connector. GO to BM19.
BM19: CHECK POWER TO BLOWER MOTOR RELAY #2
Key OFF.
Disconnect the blower motor relay #2 connector.
Key ON.
Measure the voltage on the "BK/Y" wire at the blower motor relay #2 connector.
Is the voltage greater than 10 volts?
Yes
GO to BM20.
No
SERVICE the "BK/Y" wire.
BM20: CHECK BLOWER MOTOR RELAY #2
Key OFF.
Disconnect the blower motor relay #2 connector.
Measure the resistance between the "BL/Y" and the "R/BK" wire terminals on the blower motor relay #2.
Apply 12 volts to the "BK/Y" wire terminal, and ground to the "BL/BK" wire terminal on the blower motor relay #2.
Measure the resistance between the "BL/Y" and the "R/BK" wire terminals on the blower motor relay #2.
Is the resistance less than 5 ohms when 12 volts and ground are applied, and greater than 10,000 ohms when 12 volts and ground are not applied?
Yes
GO to BM21.
No
REPLACE the blower motor relay #2.
BM21: CHECK WIRE BETWEEN BLOWER MOTOR RELAY #2 AND BLOWER SWITCH
Key OFF.
Disconnect the blower motor relay #2 connector and the blower switch connector.
Measure the resistance of the "BL/BK" wire between the blower motor relay #2 connector and the blower switch connector.
Measure the resistance of the "BL/BK" wire between the blower motor relay #2 connector and ground.
Is the resistance less than 5 ohms between the blower motor relay #2 connector and the blower switch connector, and greater than 10,000 ohms between the blower motor relay #2 connector and ground?
Yes
GO to BM22.
No
SERVICE the "BL/BK" wire.
BM22: CHECK WIRE BETWEEN BLOWER MOTOR
RELAY #2 AND BLOWER MOTOR RESISTOR
Key OFF.
Disconnect the blower motor relay #2 connector and the blower motor resistor connector on the blower assembly.
Measure the resistance of the "R/BK" wire between the blower motor relay #2 connector and the blower motor resistor connector.
Measure the resistance of the "R/BK" wire between the blower motor relay connector #2 and ground.
Is the resistance less than 5 ohms between the blower motor relay #2 connector and the blower motor resistor connector, and greater than 10,000 ohms between the blower motor relay #2 connector and ground?
Yes
SERVICE the "BL/Y" wire between the blower motor relay #2 connector and the mode selector switch connector.
No
SERVICE the "R/BK" wire.