Pinpoint Test T: The Auxiliary Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test T: The Auxiliary Blower Motor is Inoperative
Refer to Wiring Diagram Set 52, Auxiliary Climate Control for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, when the Rear Heating Ventilation Air Conditioning (RHVAC) module auxiliary blower motor speed is adjusted, the RHVAC module sends the selected blower motor speed from the RHVAC module over the Medium Speed Controller Area Network (MS-CAN) bus to the HVAC module. When the auxiliary blower motor speed is selected on the Front Display Interface Module (FDIM) touch screen, the FDIM sends the selected blower motor speed from the FDIM over the MS-CAN bus to the HVAC module.
The auxiliary blower motor relay coil receives a ground from the HVAC module. Voltage is supplied to the relay switch contact and coil. When the relay coil is energized, voltage is delivered from the relay to the auxiliary blower motor speed control and auxiliary blower motor. The auxiliary blower motor speed control is grounded. The HVAC module provides a Pulse-Width Modulation (PWM) signal to the auxiliary blower motor speed control to control the blower speed. Ground for the motor is provided from the auxiliary blower motor speed control.
- DTC B10B0:12 (Rear Blower Fan Relay: Circuit Short to Battery) - The module senses excessive voltage on the relay coil ground circuit, indicating a short to voltage.
- DTC B10B0:13 (Rear Blower Fan Relay: Circuit Open) - The module senses no voltage on the relay coil ground circuit, indicating an open.
- DTC B10BA:12 (Rear Blower Control: Circuit Short to Battery) - The module senses excessive voltage on the relay coil ground circuit, indicating a short to voltage.
- DTC B10BA:14 (Rear Blower Control: Circuit Short to Ground or Open) - The module senses no voltage on the blower motor control PWM circuit, indicating an open or a short to ground.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- HVAC module
- Auxiliary blower motor speed control
- Auxiliary blower motor relay
PINPOINT TEST T: THE AUXILIARY BLOWER MOTOR IS INOPERATIVE
-------------------------------------------------
T1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- Check the HVAC module for DTCs.
- Are DTCs present?
Yes
For DTC B10B0:12, REPAIR circuit CH112 (VT/WH) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For DTC B10B0:13, CARRY OUT the blower motor relay component test.
If the relay tests OK, GO to T2.
For DTC B10BA:12, REPAIR circuit VHA25 (BN/VT) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For DTC B10BA:14, GO to T3.
No
GO to T4.
-------------------------------------------------
T2 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay.
- Ignition ON.
- Measure the voltage between auxiliary blower motor relay socket pin 1, circuit CBP43 (GY) and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CH112 (VT/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
VERIFY Smart Junction Box (SJB) fuse 43 (10A) is OK. If OK, REPAIR circuit CBP43 (GY) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
-------------------------------------------------
T3 CHECK CIRCUIT VHA25 (BN/VT) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Speed Control C3002.
- Disconnect: HVAC Module C228b.
- Measure the resistance between auxiliary blower motor control C3002-5, circuit VHA25 (BN/VT), harness side and HVAC module C2356B-13, circuit VHA25 (BN/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new auxiliary blower motor speed control. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the blower motor is still inoperative, GO to T11.
No
REPAIR circuit VHA25 (BN/VT) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------
T4 CHECK CIRCUIT GD149 (BK/GY) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Speed Control C3002.
- Measure the resistance between auxiliary blower motor speed control C3002-6, circuit GD149 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to T5.
No
REPAIR circuit GD149 (BK/GY) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------
T5 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROLLER
- Ignition ON.
- Press the PANEL button on the HVAC module.
- Measure the voltage between auxiliary blower motor speed control C3002-2, circuit CHA02 (BN/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T7.
No
CARRY OUT the auxiliary blower motor relay component test.
If the relay tests OK, GO to T6.
-------------------------------------------------
T6 CHECK THE RELAY SWITCH VOLTAGE CIRCUIT FOR AN OPEN
- Measure the voltage between auxiliary blower motor relay socket pin 5, circuit SBB31 (WH/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CHA02 (BN/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
VERIFY Battery Junction Box (BJB) fuse 31 (40A) is OK. If OK, REPAIR circuit SBB31 (WH/RD) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If not OK,
REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
-------------------------------------------------
T7 CHECK FOR VOLTAGE TO THE BLOWER MOTOR
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C3021.
- Ignition ON.
- Press the PANEL button on the HVAC controls.
- Measure the voltage between auxiliary blower motor C3021-2, circuit CHA02 (BN/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T8.
No
REPAIR circuit CHA02 (BN/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------
T8 CHECK THE BLOWER MOTOR
- Ignition OFF.
- Connect: Auxiliary Blower Motor C3021.
- Disconnect: Auxiliary Blower Motor Speed Control C3002.
- Ignition ON.
- Connect a fused jumper lead between auxiliary blower motor speed control C3002-6, circuit GD149 (BK/GY), harness side and C3002-1, circuit VHA19 (BN), harness side.
- Does the blower motor operate?
Yes
INSTALL a new auxiliary blower motor speed control. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the blower motor is still inoperative, GO to T11.
No
GO to T9.
-------------------------------------------------
T9 CHECK CIRCUIT VHA19 (BN) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C3021.
- Measure the resistance between auxiliary blower motor control C3002-1, circuit VHA19 (BN), harness side and auxiliary blower motor C3021-1, circuit VHA19 (BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to T10.
No
REPAIR circuit VHA19 (BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------
T10 CHECK CIRCUIT VHA19 (BN) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and blower motor C3021-1, circuit VHA19 (BN), harness side.
- Is any voltage present?
Yes
REPAIR circuit VHA19 (BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
INSTALL a new auxiliary blower motor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------
T11 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.
-------------------------------------------------