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 ground through circuit GD149 (BK/GY). The relay 1 coil receives voltage from circuit CH435 (VT/GY) if any position but OFF is selected. Voltage is supplied to the relay 1 switch from circuit SBB16 (VT/RD). When the relay 1 coil is energized, voltage is delivered to the blower motor through circuit CHA02 (BN/GN). Ground for the motor is provided through circuit CHA03 (GY/OG) 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 GD149 (BK/GY).
The auxiliary blower motor relay 2 coil receives voltage from circuit CH435 (VT/GY) 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 through circuit CHA08 (GN/OG). When relay 2 is energized, the auxiliary blower motor is grounded directly through circuit GD149 (BK/GY).
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Auxiliary blower motor relay 1
- Auxiliary blower motor relay 2
- 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 CIRCUIT CHA03 (GY/OG) FOR 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 CIRCUIT CHA03 (GY/OG) FOR AN OPEN
- For early build, 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 30, circuit CHA03 (GY/OG).
- For late build, 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 CIRCUIT SBB16 (VT/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay.
- For early build, measure the voltage between auxiliary blower motor relay socket pin 30, circuit SBB16 (VT/RD) and ground.
- For late build, 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 CIRCUIT CH435 (VT/GY) FOR VOLTAGE
- For early build, measure the voltage between auxiliary blower motor relay socket pin 85, circuit CH435 (VT/GY) and ground.
- For late build, 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 CIRCUIT CH435 (VT/GY) FOR AN OPEN
- Ignition OFF.
- For early build, measure the resistance between auxiliary blower motor relay socket pin 85, circuit CH435 (VT/GY) and function selector switch C294a-3, circuit CH435 (VT/GY), harness side.
- For late build, 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 CIRCUIT GD149 (BK/GY) FOR AN OPEN
- Ignition OFF.
- For early build, measure the resistance between auxiliary blower motor relay socket pin 86, circuit GD149 (BK/GY) and ground.
- For late build, 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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