Pinpoint Test I: The Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test I: 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 ignition voltage. The coil receives ground from the HVAC module through circuit 364 (BK/LG) if any position but OFF is selected. Voltage is supplied to the relay switch contact. When the relay coil is energized, voltage is delivered to the blower motor through circuit 371 (PK/WH). Ground for the blower motor is provided through circuit 261 (OG/BK) from the blower resistor or the blower switch (HI). The blower resistor and blower switch is grounded through circuit 1205 (BK).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor
- Blower motor relay
- Blower motor switch
PINPOINT TEST I: THE BLOWER MOTOR IS INOPERATIVE
NOTICE: It is important to install relays in their correct position in the Bussed Electrical Center (BEC). Installing a relay incorrectly may cause wiring shorts or damage to modules. While carrying out diagnostics on BEC relays, have only one BEC 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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I1 CHECK CIRCUIT 261 (OG/BK) FOR GROUND
- Disconnect: Blower Motor C2066.
- Turn the function selector switch to the PANEL position.
- Turn the blower motor switch to the high position.
- Measure the resistance between blower motor connector C2066-2, circuit 261 (OG/BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to I4.
No
GO to I2.
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I2 CHECK CIRCUIT 261 (OG/BK) FOR AN OPEN
- Disconnect: Blower Motor Switch C294b.
- Measure the resistance between blower motor switch C294b-2, circuit 261 (OG/BK), harness side and blower motor C2066-2, circuit 261 (OG/BK), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to I3.
No
REPAIR circuit 261 (OG/BK) for an open. TEST the system for normal operation.
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I3 CHECK CIRCUIT 1205 (BK) FOR AN OPEN
- Measure the resistance between blower motor switch C294b-1, circuit 1205 (BK), 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 1205 (BK) for an open. TEST the system for normal operation.
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I4 CHECK BLOWER MOTOR CIRCUIT 371 (PK/WH) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between blower motor connector C2066-1, circuit 371 (PK/WH), 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 I5.
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I5 CHECK CIRCUIT 371 (PK/WH) FOR AN OPEN
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test probe.
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket, circuit 371 (PK/WH) and blower motor C2066-1, circuit 371 (PK/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to I6.
No
REPAIR circuit 371 (PK/WH) for an open. TEST the system for normal operation.
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I6 CHECK THE BLOWER MOTOR RELAY
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test probe.
- Connect: Blower Motor C2066.
- Ignition ON.
- Connect a fused jumper lead between blower motor relay socket and blower motor relay socket, circuit 371 (PK/WH).
- Does the blower motor operate?
Yes
GO to I7.
No
VERIFY Bussed Electrical Center (BEC) fuse 2 (30A) is OK. If OK, INSTALL a new BEC. If not OK, refer to the Wiring
Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation.
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I7 CHECK THE RELAY COIL SUPPLY VOLTAGE
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test probe.
- Measure the voltage between blower motor relay socket, circuit 1322 (BN/WH) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I8.
No
VERIFY the Smart Junction Box (SJB) fuse 3 (10A) is OK. If OK, REPAIR circuit 1322 (BN/WH) for an open. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation.
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I8 CHECK THE BLOWER MOTOR RELAY
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test probe.
- Ignition ON.
- Measure the voltage between blower motor relay socket, circuit 364 (BK/LG) and socket blower motor relay, circuit 1322 (BN/WH).
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to I9.
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I9 CHECK CIRCUIT 364 (BK/LG) FOR AN OPEN
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test probe.
- Ignition OFF.
- Disconnect: HVAC module C294a.
- Measure the resistance between blower motor relay socket, circuit 364 (BK/LG) and HVAC module C294a-23, circuit 364 (BK/LG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to I10.
No
REPAIR circuit 364 (BK/LG) for an open. TEST the system for normal operation.
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I10 CHECK THE MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Operate the system.
- Does the concern return?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
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