Pinpoint Test U: The Blower Motor Does Not Operate Correctly - DATC/EATC
Climate Control System
Pinpoint Tests
Pinpoint Test U: The Blower Motor Does Not Operate Correctly - DATC/EATC
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 -Electronic Automatic Temperature Control (EATC) or HVAC module - Dual Automatic Temperature Control (DATC) module through circuit CH123 (VT/GN). The coil receives ignition voltage through circuit A_CBP23 (BN/YE). 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 control module through circuit CH402 (YE/GN). Ground for the blower control module is provided by circuit GD115 (BK/GY). The HVAC module - DATC or HVAC module - EATC module provides a pulsed ground to the blower control module through circuit VH101 (WH/VT) to control the blower speed. Voltage for the motor is provided through circuit CH218 (GN/VT) from the blower control module. Ground for the motor is provided through circuit VH301 (YE/BU) from the blower control module.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor control module
- Blower motor relay
- HVAC module - EATC
- HVAC module - DATC
PINPOINT TEST U: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - DATC/EATC
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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U1 VERIFY THE BLOWER MOTOR OPERATION
- Ignition ON.
- Press the panel button on the HVAC module. Adjust the blower motor setting to LO and then to HI.
- Does the blower motor operate at any setting?
Yes
If the blower motor operates always in HI, GO to U2.
If the blower motor is always ON, GO to U5.
No
Go To Pinpoint Test T. Pinpoint Test T: The Blower Motor Is Inoperative - DATC/EATC
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U2 CHECK CIRCUIT VH101 (WH/VT) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Disconnect: HVAC Module - DATC Module C2356b or HVAC Module - EATC C228b.
- Measure the resistance between ground and blower motor speed control C271-B, circuit VH101 (WH/VT), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to U3.
No
REPAIR circuit VH101 (WH/VT) for a short to ground. TEST the system for normal operation.
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U3 CHECK CIRCUIT CH218 (GN/VT) FOR A SHORT TO VOLTAGE
- Disconnect: Blower Motor C288.
- Ignition ON.
- Measure the voltage between ground and blower motor speed control C271-E, circuit CH218 (GN/VT), harness side.
- Is any voltage present?
Yes
REPAIR circuit CH218 (GN/VT) for a short to voltage. TEST the system for normal operation.
No
GO to U4.
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U4 CHECK CIRCUIT VH301 (YE/BU) FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and blower motor C288-B, circuit VH301 (YE/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new blower control. TEST the system for normal operation. If the condition returns, GO to U6.
No
REPAIR circuit VH301 (YE/BU) for a short to voltage. TEST the system for normal operation.
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U5 CHECK CIRCUIT CH123 (VT/GN) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Disconnect: HVAC Module - DATC Module C2356a or HVAC module - EATC C228a.
- Measure the resistance between blower motor relay socket pin 85, circuit CH123 (VT/GN) and ground.
- Is the resistance greater than 10,000 ohms?
Yes
CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to U6.
No
REPAIR circuit CH123 (VT/GN) for a short to ground. TEST the system for normal operation.
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U6 CHECK MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module - Electronic Automatic Temperature Control (EATC) and HVAC Module - Dual Automatic Temperature Control (DATC) On-Demand Self Test.
- 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.