Pinpoint Test J: The Blower Motor Does Not Operate Correctly
Climate Control System
Pinpoint Tests
Pinpoint Test J: The Blower Motor Does Not Operate Correctly
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 261 (OG/BK). The resistor gets a ground from circuit 1205 (BK) in the lowest blower setting. In MED-LO and MED-HI, the resistor gets a ground through circuit 754 (LG/WH) or 752 (YE/RD), depending on selected speed. In HI, the blower motor is grounded directly through the blower switch from circuit 261 (OG/BK) to circuit 1205 (BK). The blower switch receives its ground from circuit 1205 (BK).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor resistor
- Blower motor switch
PINPOINT TEST J: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY
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J1 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 speed position?
Yes
If the blower motor does not operate in HI setting only, GO to J2.
If the blower motor does not operate in LO setting only, GO to J3.
If the blower motor does not operate in MED-LO or MED-HI setting only, GO to J4.
If the blower motor operates in HI setting only, GO to J6.
If the blower motor operates in LO setting only, GO to J7.
For all other symptoms, GO to J8.
No
Go To Pinpoint Test I. Pinpoint Test I: The Blower Motor Is Inoperative
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J2 CHECK CIRCUIT 261 (OG/BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294b.
- Disconnect: Blower Motor C2066.
- Measure the resistance between blower motor switch C294b-2, circuit 261 (OG/BK) and blower motor C2066-2, circuit 261 (OG/BK).
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit 261 (OG/BK) for an open. TEST the system for normal operation.
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J3 CHECK BLOWER MOTOR RESISTOR GROUND CIRCUIT 1205 (BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Resistor C2185.
- Measure the resistance between blower motor resistor C2185-4, circuit 1205 (BK) and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation.
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J4 CHECK CIRCUIT 752 (YE/RD) OR 754 (LG/WH) FOR AN OPEN
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 OFF.
- Disconnect: Blower Motor Resistor C2185.
- 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 lamp between blower motor resistor C2185-2, circuit 261 (OG/BK), harness side and blower motor resistor C2185-1, circuit 752 (YE/RD), 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 lamp between blower motor resistor C2185-2, circuit 261 (OG/BK), harness side and blower motor resistor C2185-3, circuit 754 (LG/WH), harness side.
- Does the test lamp illuminate?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
GO to J5.
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J5 CHECK CIRCUIT 752 (YE/RD) OR 754 (LG/WH) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294b.
For MED-LO inoperative
- For MED-LO inoperative, measure the resistance between blower motor switch C294b-4, circuit 752 (YE/RD), harness side and blower motor resistor C2185-1, circuit 752 (YE/RD), harness side.
For MED-HI inoperative
- For MED-HI inoperative, measure the resistance between blower motor switch C294b-3, circuit 754 (LG/WH), harness side and blower motor resistor C2185-3, circuit 754 (LG/WH), 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. Resistor - Blower Motor
No
REPAIR circuit 752 (YE/RD) or 754 (LG/WH) for an open. TEST the system for normal operation.
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J6 CHECK BLOWER MOTOR RESISTOR CIRCUIT 261 (OG/BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Resistor C2185.
- Connect: Blower Motor C2066.
- Measure the resistance between blower motor resistor C2185-2, circuit 261 (OG/BK) and blower motor C2066-2, circuit 261 (OG/BK).
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor resistor. TEST the system for normal operation.
No
REPAIR circuit 261 (OG/BK) for an open. TEST the system for normal operation.
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J7 CHECK BLOWER MOTOR SWITCH CIRCUIT 1205 (BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Switch C294b.
- Measure the resistance between blower motor switch C294b-1, circuit 1205 (BK) and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation.
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J8 CHECK CIRCUITS 261 (OG/BK), 752 (YE/RD) AND 754 (LG/WH) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor C2066.
- Disconnect: Blower Motor Switch C294b.
- Disconnect: Blower Motor Resistor C2185.
- Measure the resistance between ground and blower motor resistor C2185, circuit:
- 752 (YE/RD) pin 1
- 261 (OG/BK) pin 2
- 754 (LG/WH) pin 3
- Are the resistances greater than 10,000 ohms?
Yes
GO to J9.
No
REPAIR the affected circuit. TEST the system for normal operation.
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J9 CHECK THE BLOWER MOTOR CIRCUITS FOR SHORTS TOGETHER
- Measure the resistance between blower motor resistor C2185:
- pin 1, circuit 752 (YE/RD) and pin 2, circuit 261 (OG/BK).
- pin 1, circuit 752 (YE/RD) and pin 3, circuit 754 (LG/WH).
- pin 2, circuit 261 (OG/BK) and pin 3, circuit 754 (LG/WH).
- Are the resistances greater than 10,000 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. Resistor - Blower Motor
No
REPAIR the affected circuits. TEST the system for normal operation.
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