Pinpoint Test T: The Auxiliary Blower Motor Does Not Operate Correctly
Climate Control System
Pinpoint Tests
Pinpoint Test T: The Auxiliary Blower Motor Does Not Operate Correctly
Refer to Wiring Diagram Set 52, Auxiliary Climate Control for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, 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). The blower motor speed relay coils are supplied through circuit CBP45 (YE). Blower motor speed is received by the HVAC module - Dual Automatic Temperature Control (DATC) from the rear auxiliary control through circuit VHA17 (VT/GN). Reference voltage for the blower speed selector resistor is provided by the HVAC module - DATC through circuit LH111 (BN/WH). When the relay 1 coil is energized, voltage is delivered to the blower motor through circuit CHA02 (BN/GN). The auxiliary blower motor relay coil receives ground from the HVAC module - DATC through circuit CH112 (VT/WH) if any blower speed but OFF is selected.
In LO, ground for the blower motor is provided through the blower motor resistor.
In MED-LO, blower motor speed relay 3 is grounded by the HVAC module - DATC through circuit CH114 (GN/WH). Blower motor ground circuit CHA03 (GY/OG) is connected through one half of the blower motor resistor to circuit CHA04 (GN/WH). Circuit CHA04 (GN/WH) is connected through blower motor speed relay 3 to the blower motor resistor through circuit ZA110 (OG/YE). The blower resistor is grounded through circuit GD147 (BK/VT).
In MED-HI, blower motor relay 2 is grounded by the HVAC module - DATC through circuit CH113 (VT/GY). Blower motor ground circuit CHA03 (GY/OG) is connected through blower motor speed relay 2 to circuit CHA04 (GN/WH). Circuit CHA04 (GN/WH) is connected through one half of the blower motor resistor to the blower motor resistor to ground circuit GD147 (BK/VT).
In HI, blower motor speed relays 2 and 3 are grounded by the HVAC module - DATC through circuit CH114 (GN/WH) and CH113 (VT/GY). Blower motor ground circuit CHA03 (GY/OG) is connected through blower motor speed relay 2 to circuit CHA04 (GN/WH). Circuit CHA04 (GN/WH) is connected through blower motor speed relay 3 to the blower motor resistor ground circuit GD147 (BK/VT) by circuit ZA110 (OG/YE).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Auxiliary blower motor relay
- Auxiliary blower motor speed relay 1
- Auxiliary blower motor speed relay 2
- Auxiliary blower motor speed relay 3
- Auxiliary blower motor resistor
- HVAC module - DATC
PINPOINT TEST T: THE AUXILIARY BLOWER MOTOR DOES NOT OPERATE CORRECTLY
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T1 CHECK AUXILIARY BLOWER MOTOR OPERATION
- Ignition ON.
- Turn the auxiliary climate controls OFF.
- Is the auxiliary blower motor ON?
Yes
CARRY OUT the relay component test on the auxiliary blower motor relay 1. If OK, GO to T2.
No
GO to T4.
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T2 CHECK CIRCUIT CHA02 (BN/GN) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C3021.
- Disconnect: Auxiliary Blower Motor Speed Relay 1 .
- Ignition ON.
- Measure the voltage between auxiliary blower motor relay 1 socket pin 87, circuit CHA02 (BN/GN) and ground.
- Is any voltage present?
Yes
REPAIR circuit CHA02 (BN/GN) for a short to voltage. TEST the system for normal operation.
No
GO to T3.
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T3 CHECK CIRCUITS CH112 (VT/WH) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: HVAC Module - DATC C228b.
- Measure the resistance between ground and auxiliary blower motor relay 1 socket pin 86, circuit CH112 (VT/WH).
- Is the resistance greater than 10,000 ohms?
Yes
GO to T14.
No
REPAIR circuit CH112 (VT/WH) for a short to ground. TEST the system for normal operation.
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T4 CHECK AUXILIARY BLOWER MOTOR OPERATION
- Select all auxiliary blower speeds.
- Is the auxiliary blower motor always one speed?
Yes
GO to T5.
No
GO to T6.
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T5 CHECK CIRCUIT CHA03 (GY/OG) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Resistor C3022.
- Measure the resistance between auxiliary blower motor relay 2 socket pin 87, circuit CHA03 (GY/OG) and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to T14.
No
REPAIR circuit CHA03 (GY/OG) for a short to ground. TEST the system for normal operation.
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T6 CHECK AUXILIARY BLOWER MOTOR OPERATION
- Select all auxiliary blower speeds.
- Is the auxiliary blower motor inoperative in any speed?
Yes
CARRY OUT the component test on the auxiliary blower motor resistor. If OK, REPAIR circuit CHA03 (GY/OG) for an open between the blower motor resistor and splice S396. TEST the system for normal operation. Resistor - Auxiliary Blower Motor
No
CARRY OUT the relay component test on the auxiliary blower motor relay 2 and 3. If OK, GO to T7.
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T7 CHECK CIRCUIT CBP45 (YE) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Speed Relay 2 and 3.
- Ignition ON.
- Measure the voltage between auxiliary blower motor relay 2 and 3 socket pin 85, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T8.
No
REPAIR circuit CBP45 (YE) for an open. TEST the system for normal operation.
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T8 CHECK CIRCUITS CH114 (GN/WH) AND CH113 (VT/GY) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: HVAC Module - DATC C228b.
- Measure the resistance between ground and:
- auxiliary blower motor relay 2 socket pin 86, circuit CH113 (VT/GY).
- auxiliary blower motor relay 3 socket pin 86, circuit CH114 (GN/WH).
- Are the resistances greater than 10,000 ohms?
Yes
GO to T9.
No
REPAIR circuit CH114 (GN/WH) or CH113 (VT/GY) for a short to ground. TEST the system for normal operation.
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T9 CHECK CIRCUITS CH114 (GN/WH) AND CH113 (VT/GY) FOR AN OPEN
- Measure the resistance between:
- HVAC module - DATC C228b-1, circuit CH114 (GN/WH), harness side and auxiliary blower motor relay 3 socket pin 86, circuit CH114 (GN/WH).
- HVAC module - DATC C228b-14, circuit CH113 (VT/GY), harness side and auxiliary blower motor relay 2 socket pin 86, circuit CH113 (VT/GY).
- Are the resistances less than 5 ohms?
Yes
GO to T10.
No
REPAIR circuit CH114 (GN/WH) or CH113 (VT/GY) for an open. TEST the system for normal operation.
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T10 CHECK CIRCUIT CHA04 (GN/WH) FOR AN OPEN
- Disconnect: Auxiliary Blower Motor Resistor C3022.
- Measure the resistance between auxiliary blower motor resistor C3022-1, circuit CHA04 (GN/WH), harness side and:
- auxiliary blower motor relay 2 socket pin 30, circuit CHA04 (GN/WH).
- auxiliary blower motor relay 3 socket pin 30, circuit CHA04 (GN/WH).
- Are the resistances less than 5 ohms?
Yes
GO to T11.
No
REPAIR circuit CHA04 (GN/WH) for an open. TEST the system for normal operation.
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T11 CHECK CIRCUIT CHA04 (GN/WH) FOR A SHORT TO GROUND
- Measure the resistance between ground and auxiliary blower motor relay 2 and 3 socket pin 86, circuit CHA04 (GN/WH).
- Is the resistance greater than 10,000 ohms?
Yes
GO to T12.
No
REPAIR circuit CHA04 (GN/WH) for a short to ground. TEST the system for normal operation.
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T12 CHECK CIRCUIT ZA110 (OG/YE) FOR AN OPEN
- Measure the resistance between auxiliary blower motor resistor C3022-3, circuit ZA110 (OG/YE), harness side and auxiliary blower motor relay 3 socket pin 87, circuit ZA110 (OG/YE).
- Is the resistance less than 5 ohms?
Yes
GO to T13.
No
REPAIR circuit ZA110 (OG/YE) for an open. TEST the system for normal operation.
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T13 CHECK CIRCUITS CHA04 (GN/WH), ZA110 (OG/YE) AND CHA03 (GY/DG) FOR A SHORT TOGETHER
- Measure the resistance between auxiliary blower motor resistor:
- C3022-4, circuit CHA03 (GY/DG), harness side and auxiliary blower motor resistor C3022-1, circuit CHA04 (GN/WH), harness side.
- C3022-4, circuit CHA03 (GY/DG), harness side and auxiliary blower motor resistor C3022-3, circuit ZA110 (OG/YE), harness side.
- C3022-1, circuit CHA04 (GN/WH), harness side and auxiliary blower motor resistor C3022-3, circuit ZA110 (OG/YE), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
REPAIR circuit CHA03 (GY/OG) for an open between auxiliary blower motor relay 2 and the auxiliary blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit CHA04 (GN/WH), ZA110 (OG/YE) or CHA03 (GY/OG) for a short together. TEST the system for normal operation.
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T14 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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