Pinpoint Test Q: The Blower Motor Does Not Operate Correctly - Manual Climate Control
Climate Control System
Pinpoint Tests
Pinpoint Test Q: The Blower Motor Does Not Operate Correctly - Manual Climate Control
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, when the high-speed blower relay is not energized, the blower motor is provided a ground from the resistor. The resistor is provided ground in the lowest blower setting. In MED-LO and MED-HI, the resistor gets a ground from the blower motor switch, depending on selected speed. The blower motor switch is grounded.
The high-speed blower motor relay coil receives voltage from the blower motor relay. The coil receives ground from the function selector switch when the highest blower speed is selected. Ground for high blower speed is provided to the high-speed blower relay when the relay is energized. The high-speed blower motor relay provides the blower motor ground.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor resistor
- Blower motor switch
- High-speed blower motor relay
PINPOINT TEST Q: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - MANUAL CLIMATE CONTROL
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Q1 CHECK THE BLOWER MOTOR OPERATION
- Ignition ON.
- Turn the function selector switch to the FLOOR position.
- Select all blower speed positions.
- Does the blower motor operate in any position?
Yes
If the blower motor does not operate in HI setting only, GO to Q2.
If the blower motor does not operate in LO setting only, GO to Q6.
If the blower motor does not operate in MED-LO or MED-HI setting only, GO to Q7.
If the blower motor operates in HI setting only, GO to Q9.
If the blower motor operates in LO setting only, GO to Q10.
For all other symptoms, GO to Q11.
No
GO to Pinpoint Test P. Pinpoint Test P: The Blower Motor Is Inoperative - Manual Climate Control
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Q2 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: High-Speed Blower Motor Relay.
- Ignition ON.
- Place the function selector switch in FLOOR and the blower motor switch in HI.
- Measure the voltage between ground and high-speed blower motor relay pin 86, circuit CH402 (YE/GN).
- Is the voltage greater than 10 volts?
Yes
GO to Q3.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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Q3 CHECK THE HIGH-SPEED BLOWER MOTOR RELAY CIRCUIT GD140 (BK/GN) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between ground and high-speed blower motor relay socket pin 87, circuit GD140 (BK/GN).
- Is the resistance less than 5 ohms?
Yes
GO to Q4.
No
REPAIR circuit GD140 (BK/GN) for an open. TEST the system for normal operation.
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Q4 CHECK CIRCUIT CH430 (VT/OG) FOR AN OPEN
- Disconnect: Blower Motor Switch C294A.
- Measure the resistance between high-speed blower motor relay socket pin 85, circuit CH430 (VT/OG) and the blower motor switch C294A-2, circuit CH430 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to Q5.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
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Q5 CHECK CIRCUIT CH430 (VT/OG) FOR A SHORT TO GROUND
- Disconnect: Blower Motor Switch C294A.
- Measure the resistance between ground and blower motor switch C294A-2, circuit CH430 (VT/OG), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit CH430 (VT/OG) for a short to ground. TEST the system for normal operation.
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Q6 CHECK BLOWER MOTOR RESISTOR GROUND CIRCUIT GD140 (BK/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Resistor C293.
- Measure the resistance between ground and blower motor resistor C293-4, circuit GD140 (BK/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit GD140 (BK/GN) for an open. TEST the system for normal operation.
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Q7 CHECK THE BLOWER MOTOR SWITCH
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. 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.
- Ignition OFF.
- Disconnect: Blower Motor Resistor C293.
- Ignition ON.
For MED-LO inoperative
- For MED-LO inoperative: With the blower motor switch in the MED-LO speed position, connect a 12-volt test light between blower motor resistor C293-2, circuit CH446 (BU/BN), harness side and blower motor resistor C293-3, circuit CH428 (GN/WH), harness side.
For MED-HI inoperative
- For MED-HI inoperative: With the blower motor switch in the MED-HI speed position, connect a 12-volt test light between blower motor resistor C293-2, circuit CH446 (BU/BN), harness side and blower motor resistor C293-1, circuit CH429 (GY/BN), harness side.
- Does the test light illuminate?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
GO to Q8.
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Q8 CHECK CIRCUIT CH428 (GN/WH) OR CH429 (GY/BN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294A.
For MED-LO inoperative
- For MED-LO inoperative: Measure the resistance between blower motor switch C294A-4, circuit CH428 (GN/WH), harness side and blower motor resistor C293-3, circuit CH428 (GN/WH), harness side.
For MED-HI inoperative
- For MED-HI inoperative: Measure the resistance between blower motor switch C294A-3, circuit CH429 (GY/BN), harness side and blower motor resistor C293-1, circuit CH429 (GY/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the Blower Motor Resistor component test. If the resistor tests OK, INSTALL a new blower motor switch. TEST the system for normal operation. Blower Motor Resistor
No
REPAIR circuit CH428 (GN/WH) or CH429 (GY/BN) for an open. TEST the system for normal operation.
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Q9 CHECK BLOWER MOTOR RESISTOR CIRCUIT CH446 (BN/BU) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Resistor C293.
- Disconnect: High-Speed Blower Motor Relay.
- Measure the resistance between blower motor resistor C293-2, circuit CH446 (BN/BU), harness side and high-speed blower motor relay socket pin 87A, circuit CH446 (BN/BU).
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
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Q10 CHECK THE BLOWER MOTOR SWITCH GROUND FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294A.
- Measure the resistance between ground and blower motor switch C294A-1, circuit GD138 (BK/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit GD138 (BK/WH) for an open. TEST the system for normal operation.
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Q11 CHECK CIRCUITS CH446 (BU/BN), CH429 (GY/BN) AND CH428 (GN/WH) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Switch C294A.
- Disconnect: Blower Motor C288.
- Disconnect: Blower Motor Resistor C293.
- Disconnect: High-Speed Blower Motor Relay.
- Place the blower switch in the lowest setting.
- Measure the resistance between ground and blower motor resistor:
- C293-1, circuit CH429 (GY/BN), harness side.
- C293-2, circuit CH446 (BU/BN), harness side.
- C293-3, circuit CH428 (GN/WH), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
GO to Q12.
No
REPAIR the affected circuit for a short to ground. TEST the system for normal operation.
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Q12 CHECK THE BLOWER MOTOR CIRCUITS FOR SHORTS TOGETHER
- Measure the resistance between blower motor resistor:
- C293-1, circuit CH429 (GY/BN), harness side and C293-2, circuit CH446 (BU/BN), harness side.
- C293-1, circuit CH429 (GY/BN), harness side and C293-3, circuit CH428 (GN/WH), harness side.
- C293-2, circuit CH446 (BU/BN), harness side and C293-3, circuit CH428 (GN/WH), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR the affected circuits for shorts. TEST the system for normal operation.
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