Pinpoint Test O: The Blower Motor Is Inoperative - EMTC
Climate Control System
Pinpoint Tests
Pinpoint Test O: 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 ignition voltage through circuit CBP45 (YE). The coil receives ground from the HVAC module - Electronic Manual Temperature Control (EMTC) through circuit CH123 (VT/GN). Voltage is supplied to the relay switch contact through circuit SBB35 (BU/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 CH426 (YE/OG) from the blower resistor or the blower switch (HI). The blower resistor and blower switch is grounded through circuit GD111 (BK/BU).
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor
- Blower motor relay
- Blower motor switch
- HVAC module - EMTC
PINPOINT TEST O: THE BLOWER MOTOR IS INOPERATIVE - EMTC
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O1 CHECK CIRCUIT CH426 (YE/OG) FOR GROUND
- 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 O4.
No
GO to O2.
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O2 CHECK CIRCUIT CH426 (YE/OG) FOR AN OPEN
- Disconnect: Blower Motor Switch C2357b.
- Measure the resistance between blower motor switch C2357b-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
GO to O3.
No
REPAIR circuit CH426 (YE/OG) for an open. TEST the system for normal operation.
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O3 CHECK CIRCUIT GD111 (BK/BU) FOR AN OPEN
- Measure the resistance between blower motor switch C2357b-1, circuit GD111 (BK/BU), 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 GD111 (BK/BU) for an open. TEST the system for normal operation.
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O4 CHECK A/C BLOWER MOTOR CIRCUIT CH402 (YE/GN) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between blower motor connector 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 O5.
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O5 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 C2004-1, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O6.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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O6 CHECK THE BLOWER MOTOR RELAY
- Connect: Blower Motor C2004.
- Ignition ON.
- Connect a fused jumper lead between blower motor relay socket pin 30, circuit SBB35 (BU/RD) and pin 87, circuit CH402 (YE/GN).
- Does the blower motor operate?
Yes
GO to O7.
No
VERIFY Battery Junction Box (BJB) fuse 35 (40A) is OK. If OK, REPAIR circuit SBB35 (BU/RD) for an open. TEST the system for normal operation. If not OK, Refer to the Wiring Diagrams to identify the possible causes of the circuit short.
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O7 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Measure the voltage between blower motor relay socket pin 85, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to O8.
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. If not OK, Refer to the Wiring Diagrams to identify the possible causes of the circuit short.
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O8 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 lamp probe.
- Ignition ON.
- With the engine running, connect a 12-volt test lamp between blower motor relay socket pin 86, circuit CH123 (VT/GN) and socket pin 85, circuit CBP45 (YE).
- Does the test lamp illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to O9.
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O9 CHECK CIRCUIT CH123 (VT/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - EMTC C2357b.
- Measure the resistance between blower motor relay connector pin 86, circuit CH123 (VT/GN) and HVAC module - EMTC C2357a-24, circuit CH123 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O10.
No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
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O10 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 - EMTC. 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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