Pinpoint Test O: The Blower Motor Is Inoperative - Manual Climate Control
Climate Control System
Pinpoint Tests
Pinpoint Test O: The Blower Motor is Inoperative - 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, the blower motor relay coil receives ground. The blower motor relay coil receives voltage from the function selector switch if any position but OFF is selected. The function selector switch is supplied voltage. Voltage is supplied to the relay switch contact. When the relay coil is energized, voltage is delivered to the blower motor. Ground for the blower motor is provided from the blower resister or the blower switch (HI). The blower resister and blower switch is grounded.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor
- Blower motor relay
- Function selector switch
PINPOINT TEST O: THE BLOWER MOTOR IS INOPERATIVE - MANUAL CLIMATE CONTROL
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O1 CHECK THE VOLTAGE TO THE BLOWER MOTOR
- Disconnect: Blower Motor C1227.
- Ignition ON.
- Turn the function selector switch to the FLOOR position.
- Turn the blower motor switch to the HI position.
- Measure the voltage between blower motor C1227-1, circuit 371 (PK/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to O2.
No
GO to O3.
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O2 CHECK THE BLOWER MOTOR GROUND
- Ignition OFF.
- Measure the resistance between blower motor C1227-2, circuit 261 (OG/BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor. 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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O3 CHECK CIRCUIT 371 (PK/WH) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket pin 87, circuit 371 (PK/WH), and blower motor C1227-1, circuit 371 (PK/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O4.
No
REPAIR circuit 371 (PK/WH) for an open. TEST the system for normal operation.
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O4 CHECK CIRCUIT 364 (BK/LG) FOR AN OPEN
- Measure the voltage between blower motor relay socket pin 30, circuit 364 (BK/LG) and ground.
- Is the voltage 10 volts or greater?
Yes
GO to O5.
No
VERIFY the Battery Junction Box (BJB) fuse 101 (40A) is OK. If OK, REPAIR circuit 364 (BK/LG) for an open. TEST the system for normal operation.
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O5 CHECK THE BLOWER MOTOR RELAY
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table. 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 ON.
- Connect a 12-volt test light between blower motor relay socket pin 86, circuit 249 (DB/LG), and blower motor relay socket pin 85, circuit 57 (BK).
- Does the test light illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to O6.
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O6 CHECK CIRCUIT 249 (DB/LG) FOR AN OPEN
- Measure the voltage between blower motor relay socket pin 86, circuit 249 (DB/LG) and ground.
- Is the voltage 10 volts or greater?
Yes
REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
No
GO to O7.
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O7 CHECK THE VOLTAGE TO THE CLIMATE CONTROL ASSEMBLY
- Ignition OFF.
- Disconnect: Climate Control Assembly C294A.
- Ignition ON.
- Measure the voltage between climate control assembly C294A-1 circuit 1812 (BN/WH), harness side and ground.
- Is the voltage 10 volts or greater?
Yes
GO to O8.
No
VERIFY the Central Junction Box (CJB) fuse 15 (10A) is OK. If OK, REPAIR circuit 1812 (BN/WH) for an open. TEST the system for normal operation.
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O8 CHECK CIRCUIT 249 (DB/LG) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between climate control assembly C294A-3, circuit 249 (DB/LG), harness side and blower motor relay socket pin 86, circuit 249 (DB/LG).
- Is the resistance less than 5 ohms?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
REPAIR circuit 249 (DB/LG) for an open. TEST the system for normal operation.
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