Pinpoint Test J: The Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test J: The Blower Motor is Inoperative
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 voltage from the function selector switch through circuit CH435 (VT/GY) if any position but OFF is selected. The coil receives ground through circuit GD123 (BK/GY). The function selector switch receives voltage through circuit CBP37 (WH). Voltage is supplied to the relay switch contact through circuit SBB32 (VT/RD). When the relay coil is energized, voltage is delivered to the blower motor through circuit CH402 (YE/GN). Ground for the blower motor is provided through circuit CH430 (VT/OG) from the blower resister or the blower switch (HI). The blower resister is grounded through circuit GD123 (BK/GY) and the blower switch is grounded through circuit GD116 (BK/VT).
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 J: THE BLOWER MOTOR IS INOPERATIVE
NOTICE: It is important to install relays in their correct position in the Battery Junction Box (BJB). Installing a relay incorrectly may cause wiring shorts or damage to modules. While carrying out diagnostics on BJB relays, have only one BJB relay removed at a time. Failure to follow these instructions may result in damage to the vehicle circuitry or to control modules.
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J1 CHECK THE BLOWER MOTOR GROUND
- Disconnect: Blower Motor C1227.
- Turn the blower motor switch to the HI position.
- Measure the resistance between A/C blower motor C1227-2, circuit CH430 (VT/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to J4.
No
GO to J2.
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J2 CHECK CIRCUIT CH430 (VT/OG) FOR AN OPEN
- Disconnect: Blower Motor Switch C294b.
- Measure the resistance between blower motor switch C294b-2, circuit CH430 (VT/OG), harness side and blower motor C1227-2, circuit CH430 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J3.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
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J3 CHECK CIRCUIT GD116 (BK/VT) FOR AN OPEN
- Measure the resistance between blower motor switch C294b-1, circuit GD116 (BK/VT), harness side 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 GD116 (BK/VT) for an open. TEST the system for normal operation.
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J4 CHECK A/C BLOWER MOTOR CIRCUIT CH402 (YE/GN) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between A/C blower motor C1227-1, circuit CH402 (YE/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor. TEST the system for normal operation.
No
GO to J5.
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J5 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay connector pin 87, circuit CH402 (YE/GN) and blower motor C1227-1, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J6.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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J6 CHECK THE BLOWER MOTOR RELAY
- Connect: Blower Motor C1227.
- Ignition ON.
- Connect a fused jumper lead between the blower motor relay socket pin 30, circuit SBB32 (VT/RD) and pin 87, circuit CH402 (YE/GN).
- Does the blower motor operate?
Yes
GO to J7.
No
VERIFY the BJB fuse 32 (50A) is OK. If OK, REPAIR circuit SBB32 (VT/RD) for an open. TEST the system for normal operation.
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J7 CHECK CIRCUIT GD123 (BK/GY) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor relay socket pin 86, circuit GD123 (BK/GY) and ground.
- Is the resistance less than 5 ohms?
Yes
GO to J8.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
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J8 CHECK THE BLOWER MOTOR RELAY
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 85, circuit CH435 (VT/GY) and socket pin 86, circuit GD123 (BK/GY).
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to J9.
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J9 CHECK CIRCUIT CH435 (VT/GY) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor relay connector pin 85, circuit CH435 (VT/GY) and function selector switch C294a-3, circuit CH435 (VT/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J10.
No
REPAIR circuit CH435 (VT/GY) for an open. TEST the system for normal operation.
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J10 CHECK CIRCUIT CBP37 (WH) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between blower motor switch C294a-4, circuit CBP37 (WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
VERIFY the Smart Junction Box (SJB) fuse 37 (10A) is OK. REPAIR circuit CBP37 (WH) for an open. TEST the system for normal operation.
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