Pinpoint Test P: The Blower Motor Is Inoperative - Manual Climate Control
Climate Control System
Pinpoint Tests
Pinpoint Test P: 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 a ground. The coil receives voltage from the function selector switch when any position but OFF is selected. Voltage is supplied to the relay contacts. When the relay coil is energized, voltage is delivered to the blower motor and the high-speed blower motor relay. Ground is provided from the high-speed blower motor relay to the blower motor. Voltage is supplied for the function selector switch.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor
- High-speed blower motor relay
- Blower motor relay
PINPOINT TEST P: THE BLOWER MOTOR IS INOPERATIVE - MANUAL CLIMATE CONTROL
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P1 CHECK FOR VOLTAGE TO THE BLOWER MOTOR
- Disconnect: Blower Motor C288.
- Ignition ON.
- Place the function selector switch in the FLOOR position.
- Measure the voltage between ground and blower motor C288-1, circuit CH402 (YE/GN), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to P2.
No
GO to P4.
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P2 CHECK CIRCUIT VH301 (YE/BU) FOR AN OPEN
- Ignition OFF.
- Disconnect: High-Speed Blower Motor Relay.
- Measure the resistance between blower motor C288-2, circuit VH301 (YE/BU), harness side and high-speed blower motor relay socket pin 30, circuit VH301 (YE/BU).
- Is the resistance less than 5 ohms?
Yes
GO to P3.
No
REPAIR circuit VH301 (YE/BU) for an open. TEST the system for normal operation.
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P3 CHECK THE BLOWER MOTOR
- Connect: Blower Motor C288.
- Ignition ON.
- Connect a fused jumper lead between high-speed blower motor relay socket pin 87, circuit GD140 (BK/GN) and pin 30, circuit VH301 (YE/BU).
- Does the blower motor operate?
Yes
INSTALL a new high-speed blower motor relay. TEST the system for normal operation.
No
INSTALL a new blower motor. TEST the system for normal operation.
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P4 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket pin 5, circuit CH402 (YE/GN) and blower motor C288-1, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P5.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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P5 CHECK FOR VOLTAGE TO THE BLOWER MOTOR RELAY, SWITCH SIDE
- Measure the voltage between ground and blower motor relay socket pin 3, circuit SBB16 (VT/RD).
- Is the voltage greater than 10 volts?
Yes
GO to P6.
No
VERIFY Battery Junction Box (BJB) fuse 16 (40A) is OK. If OK, REPAIR circuit SBB16 (VT/RD) for an open. TEST the system for normal operation.
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P6 CHECK CIRCUIT GD120 (BK/GN) FOR AN OPEN
- Measure the resistance between ground and blower motor relay socket pin 2, circuit GD120 (BK/GN).
- Is the resistance less than 5 ohms?
Yes
GO to P7.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
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P7 CHECK FOR VOLTAGE TO THE BLOWER MOTOR RELAY, COIL SIDE
- Ignition ON.
- Measure the voltage between ground and blower motor relay socket pin 1, circuit CH123 (VT/GN).
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to P8.
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P8 CHECK CIRCUIT CBP20 (YE/VT) FOR AN OPEN
- Ignition OFF.
- Disconnect: Function Selector Switch C294B.
- Ignition ON.
- Measure the voltage between ground and function selector switch C294B-2, circuit CBP20 (YE/VT), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to P9.
No
VERIFY the Smart Junction Box (SJB) fuse 20 (10A) is OK. If OK, REPAIR circuit CBP20 (YE/VT) for an open. TEST the system for normal operation.
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P9 CHECK THE FUNCTION SELECTOR SWITCH
- Ignition OFF.
- Carry out the Function Selector Switch component test. Function Selector Switch
- Does the function selector switch test good?
Yes
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
No
INSTALL a new function selector switch. TEST the system for normal operation.
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