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 if any position but OFF is selected. The relay coil is continuously grounded. The function selector switch receives voltage. Voltage is supplied to the relay switch contact through. When the relay coil is energized, voltage is delivered from the relay to the blower motor. Ground for the blower motor is provided through the blower resister or the blower switch (HI). The blower resister and blower switch are continuously 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 J: THE BLOWER MOTOR IS INOPERATIVE
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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 THE BLOWER MOTOR GROUND CIRCUIT 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 THE BLOWER MOTOR SWITCH GROUND CIRCUIT 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. REFER to Climate Control 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 FOR VOLTAGE TO THE BLOWER MOTOR
- 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. REFER to Climate Control Service and Repair. TEST the system for normal operation.
No
GO to J5.
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J5 CHECK THE BLOWER MOTOR VOLTAGE SUPPLY CIRCUIT 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 THE BLOWER MOTOR RELAY COIL GROUND CIRCUIT
- 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
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table or equivalent. 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 85, circuit CH435 (VT/GY) and socket pin 86, circuit GD123 (BK/GY).
- Does the test light illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to J9.
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J9 CHECK THE BLOWER MOTOR RELAY COIL SWITCHED VOLTAGE CIRCUIT 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 FOR VOLTAGE TO THE FUNCTION SELECTOR SWITCH
- 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. REFER to Climate Control 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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