Pinpoint Test M: The Blower Motor Does Not Operate Correctly

Climate Control System

Pinpoint Tests

Pinpoint Test M: 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. The resistor gets a ground through the entire resistor in the lowest blower setting. In MED-LO and MED-HI, the resistor gets a ground from the blower motor switch. In HI, the blower motor is grounded directly through the blower motor switch to. The blower switch is grounded.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor resistor
- Blower motor switch

PINPOINT TEST M: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY

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M1 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 M2.

If the blower motor does not operate in LO setting only, GO to M3.

If the blower motor does not operate in MED-LO or MED-HI setting only, GO to M4.

If the blower motor operates in HI setting only, GO to M6.

If the blower motor operates in LO setting only, GO to M7.

For all other symptoms, GO to M8.

No
GO to Pinpoint Test L. Pinpoint Test L: The Blower Motor is Inoperative

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M2 CHECK CIRCUIT VH301 (YE/BU) FOR AN OPEN

- Ignition OFF.
- Disconnect: Blower Motor Switch C2357B.
- Disconnect: Blower Motor C2004.
- Measure the resistance between blower motor switch C2357B-2, circuit VH301 (YE/BU), harness side and blower motor C2004-1, circuit VH301 (YE/BU), harness side.

- Is the resistance less than 5 ohms?

Yes
INSTALL a new blower motor resistor. REFER to Climate Control Service and Repair. 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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M4 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.

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 C293-4, circuit VH301 (YE/BU), harness side and blower motor resistor C293-1, 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 C293-4, circuit VH301 (YE/BU), harness side and blower motor resistor C293-2, circuit CH429 (GY/BN), harness side.
- Does the test light illuminate?

Yes
INSTALL a new blower motor resistor. REFER to Climate Control Service and Repair. TEST the system for normal operation.

No
GO to M5.

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M5 CHECK CIRCUIT CH428 (GN/WH) OR CH429 (GY/BN) FOR AN OPEN

- Ignition OFF.
- Disconnect: Blower Motor Switch C2357B.
- Disconnect: Blower Motor Resistor C293.

For MED-LO inoperative

- For MED-LO inoperative, measure the resistance between blower motor switch C2357B-4, circuit CH428 (GN/WH), harness side and blower motor resistor C293-1, circuit CH428 (GN/WH), harness side.

For MED-HI inoperative

- For MED-HI inoperative, measure the resistance between blower motor switch C2357B-3, circuit CH429 (GY/BN), harness side and blower motor resistor C293-2, circuit CH429 (GY/BN), harness side.
- Is the resistance less than 5 ohms?

Yes
CARRY OUT the Blower Motor Resistor component test. Climate Control System If the resistor tests OK, INSTALL a new blower motor switch. REFER to Climate Control Blower Motor Switch. TEST the system for normal operation.

No
REPAIR circuit CH428 (GN/WH) or CH429 (GY/BN) for an open. TEST the system for normal operation.

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M6 CHECK CIRCUIT VH301 (YE/BU) FOR AN OPEN

- Ignition OFF.
- Disconnect: Blower Motor Resistor C293.
- Connect: Blower Motor C2004.
- Measure the resistance between blower motor resistor C293-4, circuit VH301 (YE/BU), harness side and blower motor C2004-1, circuit VH301 (YE/BU), harness side.

- Is the resistance less than 5 ohms?

Yes
INSTALL a new blower motor resistor. REFER to Climate Control Service and Repair. TEST the system for normal operation.

No
REPAIR circuit VH301 (YE/BU) for an open. TEST the system for normal operation.

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M7 CHECK THE BLOWER MOTOR SWITCH GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.
- Disconnect: Blower Motor Switch C2357B.
- Measure the resistance between blower motor switch C2357B-1, circuit GD138 (BK/WH), harness side and ground.

- Is the resistance less than 5 ohms?

Yes
INSTALL a new blower motor switch. REFER to Climate Control 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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M8 CHECK CIRCUITS VH301 (YE/BU), CH428 (GN/WH) AND CH429 (GY/BN) FOR A SHORT TO GROUND

- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Disconnect: Blower Motor Resistor C293.
- Disconnect: Blower Motor Switch C2357B.
- Place the blower switch in the lowest setting.
- Measure the resistance between ground and blower motor resistor:
- C293-1, circuit CH428 (GN/WH), harness side.
- C293-2, circuit CH429 (GY/BN), harness side.
- C293-4, circuit VH301 (YE/BU), harness side.

- Are the resistances greater than 10,000 ohms?

Yes
GO to M9.

No
REPAIR the affected circuit for a short to ground. TEST the system for normal operation.

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M9 CHECK THE BLOWER MOTOR CIRCUITS FOR SHORTS TOGETHER

- Measure the resistance between blower motor resistor:

- C293-1, circuit CH428 (GN/WH), harness side and C293-4, circuit VH301 (YE/BU), harness side.
- C293-1, circuit CH428 (GN/WH), harness side and C293-2, circuit CH429 (GY/BN), harness side.
- C293-4, circuit VH301 (YE/BU), harness side and C293-2, circuit CH429 (GY/BN), harness side.

- Are the resistances greater than 10,000 ohms?

Yes
INSTALL a new blower motor switch. REFER to Climate Control Blower Motor Switch. TEST the system for normal operation.

No
REPAIR the affected circuits. TEST the system for normal operation.

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