Pinpoint Test P: The Blower Motor is Inoperative - EMTC
Climate Control System
Pinpoint Tests
Pinpoint Test P: 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.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor
- Blower motor relay
- Blower motor switch
- Battery Junction Box (BJB)
- HVAC module - Electronic Manual Temperature Control (EMTC)
PINPOINT TEST P: THE BLOWER MOTOR IS INOPERATIVE - EMTC
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P1 CHECK CIRCUIT CH430 (VT/OG) FOR GROUND
- Disconnect: Blower Motor C288.
- 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 C288-1, circuit CH430 (VT/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to P4.
No
GO to P2.
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P2 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 C288-1, circuit CH430 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P3.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
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P3 CHECK CIRCUIT GD115 (BK/GY) FOR AN OPEN
- Measure the resistance between blower motor switch C2357B-1, circuit GD115 (BK/GY), 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 GD115 (BK/GY) for an open. TEST the system for normal operation.
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P4 CHECK A/C BLOWER MOTOR CIRCUIT CH402 (YE/GN) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between blower motor connector C288-2, 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 P5.
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P5 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 C288-2, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to P6.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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P6 CHECK THE BLOWER MOTOR RELAY
- Connect: Blower Motor C288.
- Ignition ON.
- Connect a fused (40A) jumper lead between blower motor relay socket pin 30 and pin 87, circuit CH402 (YE/GN).
- Does the blower motor operate?
Yes
GO to P7.
No
VERIFY BJB fuse 24 (40A) is OK. If OK, INSTALL a new BJB. TEST the system for normal operation.
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P7 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Measure the voltage between blower motor relay socket pin 86, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P8.
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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P8 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 at the beginning. 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 CH123 (VT/GN) and socket pin 86, circuit CBP45 (YE).
- Does the test light illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to P9.
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P9 CHECK CIRCUIT CH123 (VT/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - EMTC C2357A.
- Measure the resistance between blower motor relay connector pin 85, 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 P10.
No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
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P10 CHECK THE HVAC MODULE CONNECTION
- Inspect the 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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