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 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), 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 - Electronic Manual Temperature Control (EMTC) if any function selector 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. Ground for the blower motor is provided from the blower resistor or the blower switch (HI). The blower resistor and blower switch are grounded.
- DTC B12AF (Front Blower Motor Relay Drive Circuit Shorted to Battery Voltage) - The module senses excessive voltage on the relay coil ground circuit, indicating a short directly to voltage.
- DTC B12B0 (Front Blower Motor Relay Drive Circuit Open or Shorted to Ground) - The module senses no voltage on the relay coil ground circuit, indicating an open or a short directly to ground.
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 THE HVAC MODULE FOR DTCs
- Ignition ON.
- Check the HVAC module for DTCs.
- Are any DTCs present?
Yes
For DTC B12AF, REPAIR circuit CH123 (VT/GN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For DTC B12B0, CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to O2.
No
GO to O3.
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O2 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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O3 CHECK CIRCUIT CH430 (VT/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 C2004-1, circuit CH430 (VT/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to O6.
No
GO to O4.
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O4 CHECK CIRCUIT CH430 (VT/OG) FOR AN OPEN
- Disconnect: Blower Motor Switch C2357B.
- Measure the resistance between blower motor switch C2357B-2, circuit CH430 (VT/OG), harness side and blower motor C2004-1, circuit CH430 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O5.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
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O5 CHECK CIRCUIT GD112 (BK/GN) FOR AN OPEN
- Measure the resistance between blower motor switch C2357B-1, circuit GD112 (BK/GN), 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 GD112 (BK/GN) for an open. TEST the system for normal operation.
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O6 CHECK A/C BLOWER MOTOR CIRCUIT CH402 (YE/GN) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between blower motor C2004-2, 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 O7.
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O7 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay connector pin 5, circuit CH402 (YE/GN) and blower motor C2004-2, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O8.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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O8 CHECK THE BLOWER MOTOR RELAY
- Connect: Blower Motor C2004.
- Ignition ON.
- Connect a fused jumper lead between blower motor relay socket pin 3 and pin 5, circuit CH402 (YE/GN).
- Does the blower motor operate?
Yes
CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to O9.
No
VERIFY Battery Junction Box (BJB) fuse 12 (40A) is OK. If OK, INSTALL a new BJB. TEST the system for normal operation.
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O9 CHECK THE HVAC MODULE CONNECTION
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
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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