Pinpoint Test S: The Auxiliary Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test S: 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 ignition voltage through circuit SBB31 (WH/RD). The coil receives ground from the HVAC module - Dual Automatic Temperature Control (DATC) through circuit CH112 (VT/WH) if any auxiliary blower speed but OFF is selected. Voltage is supplied to the relay switch contact through circuit CBP45 (YE). When the relay coil is energized, voltage is delivered to the blower motor through circuit CHA02 (BN/GN). Ground for the blower motor is provided through circuit CHA03 (GY/OG) from the blower motor resistor. The blower resistor is grounded through circuit GD147 (BK/VT).
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Auxiliary blower motor
- Auxiliary blower motor relay 1
- Auxiliary blower motor resistor
PINPOINT TEST S: THE AUXILIARY BLOWER MOTOR IS INOPERATIVE
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S1 CHECK CIRCUIT CHA02 (BN/GN) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C3021.
- Ignition ON.
- Measure the voltage between auxiliary blower motor C3021-1, circuit CHA02 (BN/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to S6.
No
GO to S2.
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S2 CHECK CIRCUIT SBB31 (WH/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay 1.
- Ignition ON.
- Measure the voltage between the auxiliary blower motor relay 1 socket pin 30, circuit SBB31 (WH/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to S3.
No
VERIFY Battery Junction Box (BJB) fuse 31 (30A) is OK. If OK, REPAIR circuit SBB31 (WH/RD) for an open. TEST the system for normal operation. If not OK, Refer to the Wiring Diagrams to identify the possible causes of the circuit short.
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S3 CHECK CIRCUIT CBP45 (YE) FOR VOLTAGE
- Measure the voltage between the auxiliary blower motor relay 1 socket pin 85, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to S4.
No
VERIFY Smart Junction Box (SJB) fuse 45 (5A) is OK. If OK, REPAIR circuit CBP45 (YE) for an open. TEST the system for normal operation. If not OK, Refer to the Wiring Diagrams to identify the possible causes of the circuit short.
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S4 CHECK CIRCUIT CH112 (VT/WH) FOR GROUND
- Measure the resistance between the auxiliary blower motor relay 1 socket pin 86, circuit CH112 (VT/WH) and ground.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the relay component test on the auxiliary blower motor relay 1. If OK, REPAIR circuit CHA02 (BN/GN) for an open. TEST the system for normal operation.
No
GO to S5.
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S5 CHECK CIRCUIT CH112 (VT/WH) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - DATC C228b.
- Measure the resistance between HVAC module - DATC C228b-2, circuit CH112 (VT/WH), harness side and auxiliary blower motor relay 1 socket pin 86, circuit CH112 (VT/WH).
- Is the resistance less than 5 ohms?
Yes
GO to S8.
No
REPAIR circuit CH112 (VT/WH) for an open. TEST the system for normal operation.
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S6 CHECK CIRCUIT CHA03 (GY/OG) FOR GROUND
- Ignition OFF.
- Measure the resistance between auxiliary blower motor C3021-2, circuit CHA03 (GY/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new auxiliary blower motor. TEST the system for normal operation.
No
GO to S7.
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S7 CHECK CIRCUIT GD147 (BK/VT) FOR GROUND
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Resistor C3022.
- Measure the resistance between auxiliary blower motor resistor C3022-2, circuit GD147 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the component test on the auxiliary blower motor resistor. If OK, REPAIR circuit CHA03 (GY/OG) for an open between the auxiliary blower motor and splice S396. TEST the system for normal operation. Resistor - Auxiliary Blower Motor
No
REPAIR circuit GD147 (BK/VT) for an open. TEST the system for normal operation.
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S8 CHECK MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module - Dual Automatic Temperature Control (DATC) On-Demand Self Test. Alternate Diagnostic Methods - HVAC Module - Dual Automatic Temperature Control (DATC) Only
- Operate the system.
- Does the concern return?
Yes
INSTALL a new HVAC module - DATC. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self test. TEST the system for normal operation.
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