Pinpoint Test Q: The Blower Motor Is Inoperative - DATC
Climate Control System
Pinpoint Tests
Pinpoint Test Q: The Blower Motor is Inoperative - DATC
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the blower motor relay coil receives a ground from the HVAC module - Dual Automatic Temperature Control (DATC) through circuit CH123 (VT/GN). The coil receives ignition voltage through circuit CBP45 (YE). 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 and the blower motor control module through circuit CH402 (YE/GN). Ground for the motor is provided through circuit VH301 (YE/BU) from the blower control module. Ground for the blower control module is provided by circuit GD111 (BK/BU). The HVAC module - DATC sends a Pulse-Width Modulation (PWM) signal to the blower control module through circuit VH101 (WH/VT) to control the blower speed.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor relay
- Blower motor control module
- HVAC module - DATC
- Blower motor
PINPOINT TEST Q: THE BLOWER MOTOR IS INOPERATIVE - DATC
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Q1 VERIFY THE BLOWER MOTOR OPERATION
- Ignition ON.
- Press the PANEL button on the HVAC module - DATC. Adjust the blower motor setting to LO and then to HI.
- Is the blower motor inoperative in all settings?
Yes
GO to Q2.
No
Go To Pinpoint Test R. Pinpoint Test R: The Blower Motor Does Not Operate Correctly - DATC
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Q2 CHECK FOR VOLTAGE TO THE BLOWER MOTOR
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- 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
GO to Q3.
No
GO to Q9.
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Q3 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROL
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Ignition ON.
- Measure the voltage between blower motor speed control C271-4, circuit CH402 (YE/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Q4.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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Q4 CHECK CIRCUIT GD111 (BK/BU) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-1, circuit GD111 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to Q5.
No
REPAIR circuit GD111 (BK/BU) for an open. TEST the system for normal operation.
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Q5 CHECK CIRCUIT VH301 (YE/BU) FOR AN OPEN
- Measure the resistance between blower motor C2004-2, circuit VH301 (YE/BU), harness side and blower motor speed control C271-2, circuit VH301 (YE/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to Q6.
No
REPAIR circuit VH301 (YE/BU) for an open. TEST the system for normal operation.
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Q6 CHECK THE BLOWER MOTOR
- Connect: Blower Motor C2004.
- Connect a fused jumper lead between blower motor speed control C271-2, circuit VH301 (YE/BU), harness side and C271-1, circuit GD111 (BK/BU), harness side.
- Ignition ON.
- Does the blower motor operate?
Yes
GO to Q7.
No
INSTALL a new blower motor. TEST the system for normal operation.
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Q7 CHECK CIRCUIT VH101 (WH/VT) FOR A SHORT TO GROUND
- Ignition OFF.
- Remove the fused jumper lead from blower motor speed control C271.
- Disconnect: HVAC Module - DATC C228b.
- Measure the resistance between blower motor speed control C271-3, circuit VH101 (WH/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to Q8.
No
REPAIR circuit VH101 (WH/VT) for a short to ground. TEST the system for normal operation.
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Q8 CHECK CIRCUIT VH101 (WH/VT) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-3, circuit VH101 (WH/VT), harness side and HVAC module - DATC C228b-16, circuit VH101 (WH/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor speed control. TEST the system for normal operation. If the blower motor is still inoperative, INSTALL a new HVAC module - DATC. TEST the system for normal operation.
No
REPAIR circuit VH101 (WH/VT) for an open. TEST the system for normal operation.
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Q9 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket 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 Q10.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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Q10 CHECK THE RELAY COIL SUPPLY VOLTAGE
- 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 Q11.
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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Q11 CHECK THE RELAY SWITCH POWER CIRCUIT FOR AN OPEN
- Measure the voltage between blower motor relay socket pin 30, circuit SBB35 (BU/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Q12.
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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Q12 CHECK THE MODULE OUTPUT
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 85, circuit CBP45 (YE) and socket pin 86, circuit CH123 (VT/GN).
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to Q13.
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Q13 CHECK CIRCUIT CH123 (VT/GN) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module - DATC C228a.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 86, circuit CH123 (VT/GN) and ground.
- Is any voltage present?
Yes
REPAIR circuit CH123 (VT/GN) for a short to voltage. TEST the system for normal operation.
No
GO to Q14.
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Q14 CHECK CIRCUIT CH123 (VT/GN) FOR AN OPEN
- Measure the resistance between HVAC module - DATC C228a-24, circuit CH123 (VT/GN), harness side and blower motor relay socket pin 86, circuit CH123 (VT/GN).
- Is the resistance less than 5 ohms?
Yes
INSTALL a new HVAC module - DATC. TEST the system for normal operation.
No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
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