Pinpoint Test P: The Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test P: The Blower Motor is Inoperative
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 CH123 (VT/GN). The coil receives ignition voltage through circuit CBP45 (YE). Voltage is supplied to the relay switch contact through circuit SBB35 (BU/RD). When the relay coil is energized, voltage is delivered to the blower motor and the blower motor speed control through circuit CH402 (YE/GN). Ground for the motor is provided through circuit VH301 (YE/BU) from the blower control module. Ground for the blower control module is provided by circuit GD116 (BK/VT). The HVAC module sends a Pulse-Width Modulation (PWM) signal to the blower control module through circuit VH101 (WH/VT) to control the blower speed.
- DTC B10AF:12 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 B10AF:14 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 B10B9:14 Blower Control: Circuit Short to Ground or Open - The module senses no voltage on the blower motor speed 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
- Blower motor relay
- Blower motor speed control
- HVAC module
- Blower motor
PINPOINT TEST P: THE BLOWER MOTOR IS INOPERATIVE
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P1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- Check the HVAC module for DTCs.
- Are DTCs present?
Yes
For DTC B10AF:12, REPAIR circuit CH123 (VT/GN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For DTC B10AF:14, CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to P2.
For DTC B10B9:14, GO to P9.
No
GO to P3.
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P2 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 85, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CH123 (VT/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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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P3 VERIFY THE BLOWER MOTOR OPERATION
- Select PANEL on the HVAC module. Adjust the blower motor setting to LO and then to HI.
- Is the blower motor inoperative in all settings?
Yes
GO to P4.
No
Go To Pinpoint Test Q. Pinpoint Test Q: The Blower Motor Does Not Operate Correctly
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P4 CHECK FOR VOLTAGE TO THE BLOWER MOTOR
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Ignition ON.
- Measure the voltage between blower motor C2004-1, circuit CH402 (YE/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P5.
No
GO to P11.
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P5 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROLLER
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Ignition ON.
- Measure the voltage between blower motor speed control C271-4, circuit CH402 (YE/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P6.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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P6 CHECK CIRCUIT GD116 (BK/VT) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-1, circuit GD116 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to P7.
No
REPAIR circuit GD116 (BK/VT) for an open. TEST the system for normal operation.
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P7 CHECK CIRCUIT VH301 (YE/BU) FOR AN OPEN
- Measure the resistance between blower motor C2004-2, circuit VH301 (YE/BU), harness side and blower motor speed control C271-2, circuit VH301 (YE/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P8.
No
REPAIR circuit VH301 (YE/BU) for an open. TEST the system for normal operation.
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P8 CHECK THE BLOWER MOTOR
- Connect: Blower Motor C2004.
- Connect a fused jumper lead between blower motor speed control C271-2, circuit VH301 (YE/BU), harness side and C271-1, circuit GD116 (BK/VT), harness side.
- Ignition ON.
- Does the blower motor operate?
Yes
INSTALL a new blower motor speed control. TEST the system for normal operation. If the blower motor is still inoperative, INSTALL a new HVAC module. TEST the system for normal operation.
No
INSTALL a new blower motor. TEST the system for normal operation.
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P9 CHECK CIRCUIT VH101 (WH/VT) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: HVAC Module C228a/C2356a.
- Measure the resistance between blower motor speed control C271-3, circuit VH101 (WH/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to P10.
No
REPAIR circuit VH101 (WH/VT) for a short to ground. TEST the system for normal operation.
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P10 CHECK CIRCUIT VH101 (WH/VT) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-3, circuit VH101 (WH/VT), harness side and HVAC module C228a/C2356a-14, circuit VH101 (WH/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor speed control. TEST the system for normal operation. If the blower motor is still inoperative, INSTALL a new HVAC module. TEST the system for normal operation.
No
REPAIR circuit VH101 (WH/VT) for an open. TEST the system for normal operation.
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P11 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket pin 87, circuit CH402 (YE/GN) and blower motor C2004-1, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P12.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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P12 CHECK THE RELAY SWITCH POWER CIRCUIT FOR AN OPEN
- Measure the voltage between blower motor relay socket pin 30, circuit SBB35 (BU/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P13.
No
VERIFY Battery Junction Box (BJB) fuse 35 (40A) is OK. If OK, REPAIR circuit SBB35 (BU/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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P13 CHECK THE MODULE OUTPUT
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test lamp probe.
- Ignition ON.
- With the engine running, connect a 12-volt test lamp between blower motor relay socket pin 85, circuit CBP45 (YE) and socket pin 86, circuit CH123 (VT/GN).
- Does the test lamp illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to P14.
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P14 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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