Pinpoint Test U: The Blower Motor Is Inoperative - EMTC
Climate Control System
Pinpoint Tests
Pinpoint Test U: The Blower Motor is Inoperative - EMTC
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. The coil receives ground from the HVAC module if any function selector position but OFF is selected. Voltage is supplied to the relay switch contact. When the relay coil is grounded by the HVAC module, the relay is energized and voltage is delivered to the blower motor. Ground for the blower motor is provided from the blower resistor or the blower switch (in HI only). The blower resistor and blower switch are grounded.
- DTC B10AF:12 (Blower Fan Relay: Circuit Short to Battery) - The module senses excessive voltage on the relay coil ground circuit, indicating a short directly to voltage.
- DTC B10AF:13 (Blower Fan Relay: Circuit Open) - The module senses no voltage on the relay coil ground circuit, indicating an open.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor
- Blower motor relay
- HVAC module - Electronic Manual Temperature Control (EMTC)
PINPOINT TEST U: THE BLOWER MOTOR IS INOPERATIVE - EMTC
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U1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- Check the HVAC module for DTCs.
- Are any DTCs present?
Yes
For B10AF:12, REPAIR circuit CH123 (VT/GN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For B10AF:13, CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to U2.
No
GO to U3.
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U2 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 1, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
No
VERIFY Smart Junction Box (SJB) fuse 45 (5A) is OK. If OK, REPAIR circuit CBP45 (YE) for an open. TEST the system for normal operation.
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U3 CHECK CIRCUIT CH426 (YE/OG) FOR GROUND
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Turn the function selector switch to the PANEL position.
- Turn the blower motor switch to the HI position.
- Measure the resistance between blower motor connector C2004-2, circuit CH426 (YE/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to U5.
No
GO to U4.
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U4 CHECK CIRCUIT CH426 (YE/OG) FOR AN OPEN
- Disconnect: HVAC Module - EMTC C294B.
- Measure the resistance between HVAC module - EMTC C294B-2, circuit CH426 (YE/OG), harness side and blower motor C2004-2, circuit CH426 (YE/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
REPAIR circuit GD138 (BK/WH) for an open. TEST the system for normal operation.
No
REPAIR circuit CH426 (YE/OG) for an open. TEST the system for normal operation.
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U5 CHECK BLOWER MOTOR CIRCUIT CH402 (YE/GN) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between blower motor C2004-1, 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 U6.
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U6 CHECK CIRCUIT SBB51 (BU/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 3, circuit SBB51 (BU/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
CARRY OUT the blower motor relay component test.
If the relay tests OK, REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
No
VERIFY Battery Junction Box (BJB) fuse 51 (40A) is OK. If OK, REPAIR circuit SBB51 (BU/RD) for an open. TEST the system for normal operation.
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