Pinpoint Test P: The Blower Motor Does Not Operate Correctly - EMTC
Climate Control System
Pinpoint Tests
Pinpoint Test P: The Blower Motor Does Not Operate Correctly - EMTC
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the blower motor is provided a ground from the blower resistor through circuit CH426 (YE/OG). The resistor gets a ground from circuit GD111 (BK/BU) in the lowest blower setting. In MED-LO and MED-HI, the resistor gets a ground from the blower motor switch through circuit CH428 (GN/WH) or CH429 (GY/BN), depending on selected speed. In HI, the blower motor is grounded directly through the blower motor switch from circuit CH426 (YE/OG) to circuit GD111 (BK/BU). The blower switch receives its ground from circuit GD111 (BK/BU).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor resistor
- Blower motor switch
PINPOINT TEST P: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - EMTC
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P1 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, GO to P2.
If the blower motor does not operate in MED-HI, GO to P3.
If the blower motor does not operate in MED-LO, GO to P4.
If the blower motor does not operate in LO, GO to P5.
For all other symptoms, GO to P7.
No
Go To Pinpoint Test O. Pinpoint Test O: The Blower Motor Is Inoperative - EMTC
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P2 CHECK CIRCUIT CH426 (YE/OG) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C2357b.
- Disconnect: Blower Motor C2004.
- Measure the resistance between blower motor switch C2357b-2, circuit CH426 (YE/OG), harness side and blower motor C2004-2, circuit CH426 (YE/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P6.
No
REPAIR circuit CH426 (YE/OG) for an open. TEST the system for normal operation.
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P3 CHECK CIRCUIT CH429 (GY/BN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C2357b.
- Disconnect: Blower Motor Resistor C2185.
- Measure the resistance between blower motor switch C2357b-3, circuit CH429 (GY/BN), harness side and blower motor resistor C2185-3, circuit CH429 (GY/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P6.
No
REPAIR circuit CH429 (GY/BN) for an open. TEST the system for normal operation.
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P4 CHECK CIRCUIT CH428 (GN/WH) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C2357b.
- Disconnect: Blower Motor Resistor C2185.
- Measure the resistance between blower motor switch C2357b-4, circuit CH428 (GN/WH), harness side and blower motor resistor C2185-1, circuit CH428 (GN/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P6.
No
REPAIR circuit CH428 (GN/WH) for an open. TEST the system for normal operation.
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P5 CHECK BLOWER MOTOR RESISTOR GROUND CIRCUIT GD111 (BK/BU) FOR AN OPEN
- Measure the resistance between blower motor resistor C2185-4, circuit GD111 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to P6.
No
REPAIR circuit GD111 (BK/BU) for an open. TEST the system for normal operation.
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P6 CHECK THE BLOWER MOTOR RESISTOR
- Carry out the blower motor resistor component test. Resistor - Blower Motor
- Does the blower motor resistor test good?
Yes
GO to P7.
No
INSTALL a new blower motor resistor. TEST the system for normal operation.
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P7 CHECK THE BLOWER MOTOR SWITCH CIRCUIT GD111 (BK/BU) FOR AN OPEN
- Measure the resistance between blower motor switch C2357b-1, circuit GD111 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to P8.
No
REPAIR circuit GD111 (BK/BU) for an open. TEST the system for normal operation.
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P8 CHECK CIRCUITS CH426 (YE/OG), CH428 (GN/WH) AND CH429 (GY/BN) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Disconnect: Blower Motor Resistor C2185.
- Place the blower switch in the lowest setting.
- Measure the resistance between ground and blower motor resistor:
- C2185-1, circuit CH428 (GN/WH), harness side.
- C2185-2, circuit CH426 (YE/OG), harness side.
- C2185-3, circuit CH429 (GY/BN), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
GO to P9.
No
REPAIR the affected circuit for a short to ground. TEST the system for normal operation.
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P9 CHECK THE BLOWER MOTOR CIRCUITS FOR SHORTS TOGETHER
- Measure the resistance between blower motor resistor:
- C2185-1, circuit CH428 (GN/WH), harness side and C2185-2, circuit CH426 (YE/OG), harness side.
- C2185-1, circuit CH428 (GN/WH), harness side and C2185-3, circuit CH429 (GY/BN), harness side.
- C2185-2, circuit CH426 (YE/OG), harness side and C2185-3, circuit CH429 (GY/BN), 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. TEST the system for normal operation.
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