Pinpoint Test R: The Auxiliary Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test R: 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
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the blower motor relay coil receives a ground from the HVAC module through circuit CH112 (VT/WH). The coil receives ignition voltage through circuit CBP43 (GY). Voltage is supplied to the relay switch contact through circuit SBB13 (WH/RD). When the relay coil is energized, voltage is delivered from the relay to the blower motor control module through circuit CHA02 (BN/GN). Ground for the blower control module is provided by circuit GD149 (BK/GY). The HVAC module provides a Pulse-Width Modulation (PWM) signal to the blower control module through circuit VHA25 (BN/VT) to control the blower speed. Voltage for the motor is provided through circuit VH301 (YE/BU) from the blower control module. Ground for the motor is provided through circuit VHA19 (BN) from the blower control module.
- DTC B10B0:12 Rear Blower Fan Relay: Circuit Short to Battery - The module senses excessive voltage on the relay coil ground circuit, indicating a short directly to voltage.
- DTC B10B0:14 Rear Blower Fan Relay: Circuit Short to Ground or Open - The module senses no voltage on the relay coil ground circuit, indicating an open or a short directly to ground.
- DTC B10BA:14 Rear Blower Control: Circuit Short to Ground or Open - The module senses no voltage on the blower motor control PWM circuit, indicating an open or a short directly to ground.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- HVAC module
- Auxiliary blower motor speed control
- Auxiliary blower motor relay
PINPOINT TEST R: THE AUXILIARY BLOWER MOTOR IS INOPERATIVE
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R1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- Check the HVAC module for DTCs.
- Are DTCs present?
Yes
For DTC B10B0:12, REPAIR circuit CH112 (VT/WH) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For DTC B10B0:14, CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to R2.
For DTC B10BA:12, REPAIR circuit VHA25 (BN/VT) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For DTC B10BA:14, GO to R3.
No
GO to R4.
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R2 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay.
- Ignition ON.
- Measure the voltage between auxiliary blower motor relay socket pin 85, circuit CBP43 (GY) and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CH112 (VT/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
VERIFY Smart Junction Box (SJB) fuse 43 (10A) is OK. If OK, REPAIR circuit CBP43 (GY) for an open. CLEAR the DTCs. REPEAT the self-test. 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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R3 CHECK CIRCUIT VHA25 (BN/VT) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Speed Control C3002a.
- Disconnect: HVAC Module C228b.
- Measure the resistance between auxiliary blower motor control C3002a-3, circuit VHA25 (BN/VT), harness side and HVAC module C228b-1, circuit VHA25 (BN/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new auxiliary blower motor speed control. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the blower motor is still inoperative, GO to R11.
No
REPAIR circuit VHA25 (BN/VT) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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R4 CHECK CIRCUIT GD149 (BK/GY) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Speed Control C3002a.
- Measure the resistance between auxiliary blower motor speed control C3002a-5, circuit GD149 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to R5.
No
REPAIR circuit GD149 (BK/GY) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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R5 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROLLER
- Ignition ON.
- Press the PANEL button on the HVAC module.
- Measure the voltage between auxiliary blower motor speed control C3002a-6, circuit CHA02 (BN/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to R7.
No
CARRY OUT the auxiliary blower motor relay component test.
If the relay tests OK, GO to R6.
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R6 CHECK THE RELAY SWITCH VOLTAGE CIRCUIT FOR AN OPEN
- Measure the voltage between auxiliary blower motor relay socket pin 30, circuit SBB31 (WH/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CHA02 (BN/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
VERIFY Battery Junction Box (BJB) fuse 31 (30A) is OK. If OK, REPAIR circuit SBB31 (WH/RD) for an open. CLEAR the DTCs. REPEAT the self-test. 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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R7 CHECK THE BLOWER MOTOR
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Speed Control C3002b.
- Ignition OFF.
- Connect a fused jumper lead between auxiliary blower motor speed control C3002a-6, circuit CHA02 (BN/GN), harness side and C3002b-1, circuit VH301 (YE/BU), harness side.
- Connect a fused jumper lead between auxiliary blower motor speed control C3002a-5, circuit GD149 (BK/GY), harness side and C3002b-2, circuit VHA19 (BN), harness side.
- Does the blower motor operate?
Yes
INSTALL a new auxiliary blower motor speed control. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the blower motor is still inoperative, GO to R11.
No
GO to R8.
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R8 CHECK CIRCUITS VH301 (YE/BU) AND VHA19 (BN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C3021.
- Measure the resistance between the auxiliary blower motor connector, harness side and auxiliary blower motor speed control, harness side using the following chart.
- Are the resistances less than 5 ohms?
Yes
GO to R9.
No
REPAIR circuit CH218 (GN/VT) or VH301 (YE/BU) for an open. TEST the system for normal operation.
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R9 CHECK CIRCUIT VH301 (YE/BU) FOR A SHORT TO GROUND
- Measure the resistance between ground and blower motor C3021-1, circuit VH301 (YE/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to R10.
No
REPAIR circuit VH301 (YE/BU) for a short to ground. TEST the system for normal operation.
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R10 CHECK CIRCUIT VHA19 (BN) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and blower motor C3021-2, circuit VHA19 (BN), harness side.
- Is any voltage present?
Yes
REPAIR circuit VHA19 (BN) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new auxiliary blower motor speed control. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the blower motor is still inoperative, GO to R11.
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R11 CHECK THE MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module On-Demand Self Test. Alternate Diagnostic Methods - HVAC Module
- Operate the system.
- Does the concern return?
Yes
INSTALL a new HVAC module. 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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