Pinpoint Test T: The Auxiliary Blower Motor Is Inoperative

Climate Control System

Pinpoint Tests

Pinpoint Test T: The Auxiliary Blower Motor is Inoperative

Refer to Wiring Diagram Set 52, Auxiliary Climate Control for schematic and connector information. Diagrams By Number

Normal Operation

Under normal operation, the auxiliary blower motor relay coil receives a ground. The auxiliary blower motor relay coil receives voltage when the HVAC module - Dual Automatic Temperature Control (DATC) is ON or the function selector switch is in any position but OFF. Voltage is supplied to the auxiliary blower motor relay contacts. When the auxiliary blower motor relay coil is energized, voltage is delivered to the blower motor. Ground for the motor is provided from the blower motor resistor and blower motor switch. The blower motor resistor and blower motor switch are grounded.

This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Auxiliary blower motor
- Auxiliary blower motor relay
- Front auxiliary climate control assembly



PINPOINT TEST T: THE AUXILIARY BLOWER MOTOR IS INOPERATIVE

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T1 CHECK FOR VOLTAGE AND GROUND TO THE AUXILIARY BLOWER MOTOR


- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C3021.
- Place the front auxiliary blower motor switch in its highest setting.
- Ignition ON.
- Measure the voltage between auxiliary blower motor C3021-1, circuit CHA02 (BN/GN), harness side and C3021-2, circuit CHA08 (GN/OG), harness side.




- Is the voltage greater than 10 volts?

Yes
INSTALL a new auxiliary blower motor. TEST the system for normal operation.

No
GO to T2.

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T2 CHECK FOR VOLTAGE TO THE AUXILIARY BLOWER MOTOR


- Measure the voltage between ground and auxiliary blower motor C3021-1, circuit CHA02 (BN/GN), harness side.




- Is the voltage greater than 10 volts?

Yes
GO to T3.

No
GO to T5.

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T3 CHECK CIRCUIT CHA08 (GN/OG) FOR AN OPEN


- Ignition OFF.
- Disconnect: Front Auxiliary Climate Control Assembly C951A.
- Measure the resistance between auxiliary blower motor switch C951A-6, circuit CHA08 (GN/OG), harness side and auxiliary blower motor C3021-2, circuit CHA08 (GN/OG), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to T4.

No
REPAIR circuit CHA08 (GN/OG) for an open. TEST the system for normal operation.

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T4 CHECK CIRCUIT GD149 (BK/GY) FOR AN OPEN


- Measure the resistance between ground and front auxiliary climate control assembly C951A-1, circuit GD149 (BK/GY), harness side.




- Is the resistance less than 5 ohms?

Yes
INSTALL a new front auxiliary climate control assembly. 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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T5 CHECK CIRCUIT CHA02 (BN/GN) FOR AN OPEN


- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay.
- Measure the resistance between auxiliary blower motor relay socket pin 87, circuit CHA02 (BN/GN) and auxiliary blower motor C3021-1, circuit CHA02 (BN/GN), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to T6.

No
REPAIR circuit CHA02 (BN/GN) for an open. TEST the system for normal operation.

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T6 CHECK CIRCUIT SBB18 (YE/RD) FOR AN OPEN


- Measure the voltage between ground and auxiliary blower motor relay socket pin 30, circuit SBB18 (YE/RD).




- Is the voltage greater than 10 volts?

Yes
CARRY OUT the auxiliary blower motor relay component test.
If the relay tests OK, GO to T7.

No
VERIFY Battery Junction Box (BJB) fuse 18 (30A) is OK. If OK, REPAIR circuit SBB18 (YE/RD) for an open. TEST the system for normal operation.

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T7 CHECK CIRCUIT CH123 (VT/GN) FOR AN OPEN


- Ignition ON.
- Press the DEFROST button on the HVAC module - DATC.
- Measure the voltage between ground and auxiliary blower motor relay socket pin 85, circuit CH123 (VT/GN).




- Is the voltage greater than 10 volts?

Yes
REPAIR circuit GD140 (BK/GN) for an open. TEST the system for normal operation.

No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.

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