Pinpoint Test R: The Blower Motor Is Inoperative - EMTC
Climate Control System
Pinpoint Tests
Pinpoint Test R: 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 CBP23 (BN/YE). The coil receives ground from the HVAC module - Electronic Manual Temperature Control (EMTC) through circuit CH123 (VT/GN) if any function selector position but OFF is selected. Voltage is supplied to the relay switch contact through circuit SBB04 (GN/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 CH430 (VT/OG) from the blower resistor or the blower switch (HI). The blower resistor and blower switch are grounded through circuit GD115 (BK/GY).
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor
- HVAC module - EMTC
- Blower motor relay
- Blower motor switch
PINPOINT TEST R: THE BLOWER MOTOR IS INOPERATIVE - EMTC
NOTICE: It is important to install relays in their correct position in the Battery Junction Box (BJB). Installing a relay incorrectly may cause wiring shorts or damage to modules. While carrying out diagnostics on BJB relays, have only one BJB 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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R1 CHECK CIRCUIT CH430 (VT/OG) FOR GROUND
- Disconnect: Blower Motor C288.
- Turn the function selector switch to the VENT position.
- Turn the blower motor switch to the HI position.
- Measure the resistance between A/C blower motor C288-B, circuit CH430 (VT/OG), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to R4.
No
GO to R2.
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R2 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-B, circuit CH430 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to R3.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
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R3 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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R4 CHECK A/C BLOWER MOTOR CIRCUIT CH402 (YE/GN) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between A/C blower motor connector C288-A, 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 R5.
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R5 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-A, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to R6.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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R6 CHECK THE BLOWER MOTOR RELAY
- Connect: Blower Motor C288.
- Ignition ON.
- Connect a fused jumper lead between blower motor relay socket pin 30, circuit SBB04 (GN/RD) and pin 87, circuit CH402 (YE/GN).
- Does the blower motor operate?
Yes
GO to R7.
No
VERIFY BJB fuse 4 (40A) is OK. If OK, REPAIR circuit SBB04 (GN/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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R7 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Measure the voltage between blower motor relay socket pin 86, circuit CBP23 (BN/YE) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to R8.
No
VERIFY Smart Junction Box (SJB) fuse 23 (7.5A) is OK. If OK, REPAIR circuit CBP23 (BN/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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R8 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.
- Connect a 12-volt test lamp between blower motor relay socket pin 85, circuit CH123 (VT/GN) and socket pin 86, circuit CBP23 (BN/YE).
- Does the test lamp illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to R9.
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R9 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-23, circuit CH123 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to R10.
No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
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R10 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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