Pinpoint Test T: The Blower Motor Is Inoperative - DATC/EATC
Climate Control System
Pinpoint Tests
Pinpoint Test T: The Blower Motor is Inoperative - 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 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:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor relay
- Blower motor control
- HVAC module - EATC
- HVAC module - DATC
- Blower motor
PINPOINT TEST T: THE BLOWER MOTOR IS INOPERATIVE - 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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T1 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.
- Is the blower motor inoperative in all settings?
Yes
GO to T2.
No
Go To Pinpoint Test U. Pinpoint Test U: The Blower Motor Does Not Operate Correctly - DATC/EATC
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T2 CHECK FOR VOLTAGE TO THE BLOWER MOTOR
- Ignition OFF.
- Disconnect: Blower Motor C288.
- Ignition ON.
- Measure the voltage between blower motor C288-A, circuit CH123 (VT/GN), harness side and blower motor C288-B, circuit VH301 (YE/BU), harness side.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor. TEST the system for normal operation.
No
GO to T3.
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T3 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROLLER
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Ignition ON.
- Press the PANEL button on the HVAC module.
- Measure the voltage between blower motor speed control C271-C, circuit CH402 (YE/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T4.
No
GO to T12.
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T4 CHECK CIRCUIT GD115 (BK/GY) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-A, circuit GD115 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to T5.
No
REPAIR circuit GD115 (BK/GY) for an open. TEST the system for normal operation.
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T5 CHECK CIRCUIT VH101 (WH/VT) FOR GROUND SIGNAL
- Ignition ON.
- Press the PANEL button on the HVAC module. Adjust the blower motor setting to HI.
- Measure the voltage between blower motor speed control C271-B, circuit VH101 (WH/VT), harness side and blower motor speed control C271-C, circuit CH402 (YE/GN), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to T8.
No
GO to T6.
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T6 CHECK CIRCUIT VH101 (WH/VT) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module - EATC C228b or HVAC Module - DATC C2356b.
- Ignition ON.
- Measure the voltage between ground and blower motor speed control C271-B, circuit VH101 (WH/VT), harness side.
- Is any voltage present?
Yes
REPAIR circuit VH101 (WH/VT) for a short to voltage. TEST the system for normal operation.
No
GO to T7.
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T7 CHECK CIRCUIT VH101 (WH/VT) FOR AN OPEN
EATC
- NOTE: EATC systems only.
- Measure the resistance between blower motor control C271-B, circuit VH101 (WH/VT), harness side and HVAC module - EATC C228b-14, circuit VH101 (WH/VT), harness side.
DATC
- NOTE: DATC systems only.
- Measure the resistance between blower motor control C271-B, circuit VH101 (WH/VT), harness side and HVAC module - DATC C2356b-22, circuit VH101 (WH/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to T18.
No
REPAIR circuit VH101 (WH/VT) for an open. TEST the system for normal operation.
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T8 CHECK CIRCUITS CH218 (GN/VT) AND VH301 (YE/BU) FOR AN OPEN
- Measure the resistance between the blower motor connector, harness side and blower motor speed control, harness side using the following chart.
- Are the resistances less than 5 ohms?
Yes
GO to T9.
No
REPAIR circuit CH218 (GN/VT) or VH301 (YE/BU) for an open. TEST the system for normal operation.
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T9 CHECK CIRCUITS CH218 (GN/VT) AND VH301 (YE/BU) FOR A SHORT TOGETHER
- Measure the resistance between blower motor C288-A, circuit CH218 (GN/VT), harness side and blower motor C288-B, circuit VH301 (YE/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to T10.
No
REPAIR circuits CH218 (GN/VT) and VH301 (YE/BU) for a short together. TEST the system for normal operation.
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T10 CHECK CIRCUIT CH218 (GN/VT) FOR A SHORT TO GROUND
- Measure the resistance between ground and blower motor C288-A, circuit CH218 (GN/VT), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to T11.
No
REPAIR circuit CH218 (GN/VT) for a short to ground. TEST the system for normal operation.
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T11 CHECK CIRCUIT VH301 (YE/BU) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and blower motor C288-B, circuit VH301 (YE/BU), harness side.
- Is any voltage present?
Yes
REPAIR circuit VH301 (YE/BU) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new blower motor speed control. TEST the system for normal operation.
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T12 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 control C271-C, circuit CH402 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to T13.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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T13 CHECK THE RELAY COIL SUPPLY VOLTAGE
- 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 T14.
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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T14 CHECK THE RELAY SWITCH POWER CIRCUIT FOR AN OPEN
- Measure the voltage between blower motor relay socket pin 30, circuit SBB04 (GN/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T15.
No
VERIFY Battery Junction Box (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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T15 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.
- 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 T16.
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T16 CHECK CIRCUIT CH123 (VT/GN) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module - DATC C2356a or HVAC Module - EATC C228a.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 85, 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 T17.
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T17 CHECK CIRCUIT CH123 (VT/GN) FOR AN OPEN
- Measure the resistance between blower motor relay socket pin 85, circuit CH123 (VT/GN) and:
NOTE: EATC systems only.
- HVAC module - EATC C228a-23, circuit CH123 (VT/GN), harness side.
NOTE: DATC systems only.
- HVAC module - DATC C2356a-23, circuit CH123 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to T18.
No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
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T18 CHECK THE 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.
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