Pinpoint Test L: The Auxiliary Blower Motor is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test L: The Auxiliary Blower Motor is Inoperative
Refer to Wiring Diagram Set 52, Auxiliary Climate Control for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the auxiliary blower motor relay 1 coil receives a continuous ground. The relay 1 coil receives voltage if any position but OFF is selected. Voltage is supplied to the relay 1 switch contact. When the relay 1 coil is energized, voltage is delivered from the relay to the blower motor. Ground for the motor is provided from auxiliary blower motor relay 2. In any speed except HI, ground is provided to relay 2 switch through the auxiliary resistor. In HI, ground is provided to relay 2 switch through a continuous ground.
The auxiliary blower motor relay 2 coil receives voltage if any position but OFF is selected. When the auxiliary blower motor switch is in the HI position, ground is provided to the relay 2 coil. When relay 2 is energized, the auxiliary blower motor is grounded directly through a continuous ground.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Auxiliary blower motor relay
- Auxiliary high speed blower motor relay
- Auxiliary blower motor switch
- Auxiliary blower motor resistor
- Auxiliary blower motor
- Function selector switch
PINPOINT TEST L: THE AUXILIARY BLOWER MOTOR IS INOPERATIVE
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L1 CHECK FOR VOLTAGE TO THE AUXILIARY BLOWER MOTOR
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C4106.
- Ignition ON.
- Set the function selector switch in the FLOOR position.
- Set the auxiliary blower motor switch in the HI position.
- Measure the voltage between auxiliary blower motor C4106-1, circuit CHA02 (BN/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to L2.
No
GO to L4.
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L2 CHECK THE AUXILIARY BLOWER MOTOR GROUND
- Measure the resistance between auxiliary blower motor C4106-2, circuit CHA03 (GY/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new auxiliary blower motor relay. TEST the system for normal operation.
No
GO to L3.
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L3 CHECK THE AUXILIARY BLOWER MOTOR GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between auxiliary blower motor C4106-2, circuit CHA03 (GY/OG), harness side and the auxiliary high speed blower motor relay socket pin 3, circuit CHA03 (GY/OG).
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the relay test on the auxiliary high speed blower relay. If the relay tests good, REPAIR circuit GD149 (BK/GY). TEST the system for normal operation.
No
REPAIR circuit CHA03 (GY/OG) for an open. TEST the system for normal operation.
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L4 CHECK FOR VOLTAGE TO THE AUXILIARY BLOWER MOTOR RELAY SWITCH CONTACTS
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay.
- Measure the voltage between auxiliary blower motor relay socket pin 3, circuit SBB16 (VT/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to L5.
No
VERIFY the Battery Junction Box (BJB) fuse 16 (50A) is OK. If OK, REPAIR circuit SBB16 (VT/RD) for an open. TEST the system for normal operation.
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L5 CHECK FOR VOLTAGE TO THE AUXILIARY BLOWER MOTOR RELAY COIL
- Measure the voltage between auxiliary blower motor relay socket pin 2, circuit CH435 (VT/GY) and ground.
- Is the voltage greater than 10 volts.
Yes
GO to L7.
No
GO to L6.
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L6 CHECK THE AUXILIARY BLOWER MOTOR RELAY SWITCHED VOLTAGE CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between auxiliary blower motor relay socket pin 2, circuit CH435 (VT/GY) and function selector switch C294A-3, circuit CH435 (VT/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
REPAIR circuit CH435 (VT/GY) for an open. TEST the system for normal operation.
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L7 CHECK THE AUXILIARY BLOWER MOTOR RELAY COIL GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between auxiliary blower motor relay socket pin 1, circuit GD149 (BK/GY) and ground.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the relay test on the auxiliary blower relay. If the relay tests good, REPAIR circuit CHA02 (BN/GN). TEST the system for normal operation.
No
REPAIR circuit GD149 (BK/GY) for an open. TEST the system for normal operation.
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