Pinpoint Test Q: The Blower Motor is Inoperative

Climate Control System

Pinpoint Test Q: The Blower Motor is Inoperative

Refer to Wiring Diagrams Set 52, Auxiliary Climate Control for schematic and connector information. Electrical Diagrams

Refer to Wiring Diagrams Set 55, Automatic Climate Control System for schematic and connector information. Electrical Diagrams

Normal Operation

Under normal operation, the relay coil and switch contacts is supplied voltage. When the blower motor relay coil receives a ground from the HVAC module, the relay coil is energized and voltage is delivered to the blower motor and the blower motor speed control from the relay. Ground for the motor is provided from the blower motor speed control. Ground is provided for the blower motor speed control. The HVAC module sends a Pulse Width Modulated (PWM) signal to the blower motor speed control to control the blower speed.

- DTC B10AF:12 (Blower Fan Relay: Circuit Short to Battery)- The module senses voltage on the relay coil ground circuit when the relay is grounded by the HVAC module, indicating a short to voltage.

- DTC B10AF:13 (Blower Fan Relay: Circuit Open)- The module senses no voltage on the relay coil ground circuit when the relay is not grounded by the HVAC module, indicating an open.

- DTC B10B9:14 (Blower Control: Circuit Short to Ground or Open)- The module senses no voltage on the blower motor control PWM (Pulse Width Modulated) circuit, indicating an open or a short to ground.

This pinpoint test is intended to diagnose the following:

- Fuse(s)

- Wiring, terminals or connectors

- Blower motor relay

- Blower motor speed control

- HVAC module

- Blower motor

PINPOINT TEST Q : THE BLOWER MOTOR IS INOPERATIVE

Q1 CHECK THE HVAC MODULE FOR DTCs

- Ignition ON.

- Check the HVAC module for DTCs.

Are any DTCs present?

Yes

For DTC B10AF:12, REPAIR circuit CH123 (VT/GN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

For DTC B10AF:13, CARRY OUT the Blower Motor Relay component test.

If the relay tests OK, GO to Q2.

For DTC B10B9:14, GO to Q9.

No
GO to Q3.

Q2 CHECK THE RELAY COIL SUPPLY VOLTAGE

- Ignition OFF.

- Disconnect: Blower Motor Relay.

- Ignition ON.

- Measure the voltage between blower motor relay socket pin 1, circuit CBP45 (YE) and ground.





Is the voltage greater than 10 volts?

Yes
REPAIR circuit CH123 (VT/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

No
VERIFY Smart Junction Box (SJB) fuse 45 (5A) is OK. If OK, REPAIR circuit CBP45 (YE) 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. Electrical Diagrams

Q3 VERIFY THE BLOWER MOTOR OPERATION

- Select PANEL on the HVAC controls. Adjust the blower motor setting to LO and then to HI.

Is the blower motor inoperative in all settings?

Yes
GO to Q4.

No
GO to Pinpoint Test S. Pinpoint Test S: The Auxiliary Blower Motor is Inoperative

Q4 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 Q5.

No
GO to Q11.

Q5 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROLLER

- 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 Q6.

No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.

Q6 CHECK CIRCUIT GD116 (BK/VT) FOR AN OPEN

- Ignition OFF.

- Measure the resistance between blower motor speed control C271-1, circuit GD116 (BK/VT), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to Q7.

No
REPAIR circuit GD116 (BK/VT) for an open. TEST the system for normal operation.

Q7 CHECK CIRCUIT CH102 (YE/BU) FOR AN OPEN

- Measure the resistance between blower motor C2004-2, circuit CH102 (YE/BU), harness side and blower motor speed control C271-2, circuit CH102 (YE/BU), harness side.





Is the resistance less than 5 ohms?

Yes
GO to Q8.

No
REPAIR circuit CH102 (YE/BU) for an open. TEST the system for normal operation.

Q8 CHECK THE BLOWER MOTOR

- Connect: Blower Motor C2004.

- Connect a fused jumper lead between blower motor speed control C271-2, circuit CH102 (YE/BU), harness side and C271-1, circuit GD116 (BK/VT), harness side.





- Ignition ON.

Does the blower motor operate?

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. TEST the system for normal operation.

No
INSTALL a new blower motor. TEST the system for normal operation.

Q9 CHECK CIRCUIT VH101 (WH/VT) FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: Blower Motor Speed Control C271.

- Disconnect: HVAC Module C228A.

- 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 Q10.

No
REPAIR circuit VH101 (WH/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

Q10 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 C228A-26, 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

No
REPAIR circuit VH101 (WH/VT) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

Q11 CHECK CIRCUIT CH402 (YE/GN) FOR AN OPEN

- Ignition OFF.

- Disconnect: Blower Motor Relay.

- Measure the resistance between blower motor relay socket pin 3, 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 Q12.

No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.

Q12 CHECK THE RELAY SWITCH POWER CIRCUIT FOR AN OPEN

- Ignition ON.

- Measure the voltage between blower motor relay socket pin 5, circuit SBB35 (BU/RD) and ground.





Is the voltage greater than 10 volts?

Yes
GO to Q13.

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. Electrical Diagrams

Q13 CHECK THE MODULE OUTPUT

NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.

- Ignition ON.

- Connect a 12-volt test lamp between blower motor relay socket pin 1, circuit CBP45 (YE) and socket pin 2, circuit CH123 (VT/GN).





Does the test lamp illuminate?

Yes
INSTALL a new blower motor relay. TEST the system for normal operation.

No
GO to Q14.

Q14 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.