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 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, voltage is provided to the blower motor relay coil and switch contacts. When the blower motor relay coil receives a ground from the HVAC module, the relay coil is energized and voltage is delivered from the blower motor relay to the blower motor and the blower motor speed control. A varying ground for the blower motor is provided from the blower motor speed control. Ground is provided for the blower control module. The HVAC module sends a Pulse Width Modulated (PWM) signal to the blower motor speed control to vary the blower speed.
- DTC B10AF:12 (Blower Fan Relay: Circuit Short to Battery) - The module senses voltage on the relay coil ground circuit when the relay is grounded by the HVAC module, indicating a short directly to voltage.
- DTC B10AF:13 (Blower Fan Relay: Circuit Open) - The module senses no voltage on the relay coil ground circuit when the relay is not grounded by the HVAC module, indicating an open.
- DTC B10B9:14 (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
- 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 any 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:13, 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 BLOWER MOTOR RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 1, circuit CBB50 (YE/OG) 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 Battery Junction Box (BJB) fuse 50 (10A) is OK. If OK, REPAIR circuit CBB50 (YE/OG) 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. Diagrams By Number
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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 C2004-2, 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 SPEED CONTROL
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Ignition ON.
- Measure the voltage between blower motor speed control C271-3, 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 THE BLOWER MOTOR SPEED CONTROL GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-6, circuit GD115 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to P7.
No
REPAIR circuit GD115 (BK) for an open. TEST the system for normal operation.
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P7 CHECK THE BLOWER MOTOR GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between blower motor C2004-1, circuit CH218 (GN/VT), harness side and blower motor speed control C271-1, circuit CH218 (GN/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P8.
No
REPAIR circuit CH218 (GN/VT) 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 C271-1, circuit CH218 (GN/VT), harness side and C271-6, circuit GD115 (BK), harness side.
- Ignition ON.
- Does the blower motor operate?
Yes
INSTALL a new blower motor speed control. REFER to Climate Control Service and Repair. TEST the system for normal operation. If the blower motor is still inoperative, INSTALL a new HVAC module. REFER to Climate Control Heating Ventilation Air Conditioning (HVAC) Module. TEST the system for normal operation.
No
INSTALL a new blower motor. REFER to Climate Control Service and Repair. TEST the system for normal operation.
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P9 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Disconnect: HVAC Module C228.
- Measure the resistance between blower motor speed control C271-5, 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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P10 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-5, circuit VH101 (WH/VT), harness side and HVAC module C228-1, circuit VH101 (WH/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor speed control. REFER to Climate Control Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the blower motor is still inoperative, INSTALL a new HVAC module. REFER to Climate Control Heating Ventilation Air Conditioning (HVAC) Module. TEST the system for normal operation.
No
REPAIR circuit VH101 (WH/VT) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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P11 CHECK THE BLOWER MOTOR VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket pin 5, circuit CH402 (YE/GN) and blower motor C2004-2, 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 BLOWER MOTOR RELAY SWITCH CONTACT VOLTAGE CIRCUIT FOR AN OPEN
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 3, circuit SBB23 (WH/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P13.
No
VERIFY Battery Junction Box (BJB) fuse 23 (40A) is OK. If OK, REPAIR circuit SBB23 (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. Diagrams By Number
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P13 CHECK THE MODULE OUTPUT
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table or equivalent. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Connect a 12-volt test lamp between blower motor relay socket pin 1, circuit CBP50 (YE/OG) and socket pin 2, 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 HVAC MODULE CONNECTION
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVAC module. REFER to Climate Control Heating Ventilation Air Conditioning (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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