Pinpoint Test Q: The Blower Motor Is Inoperative
Climate Control System
Pinpoint Test Q: The Blower Motor is Inoperative
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
Voltage is provided to the blower motor relay coil and switch contacts. When the blower motor relay coil receives a ground from the HVAC module, the relay coil is energized and voltage is delivered from the blower motor relay to the blower motor. A varying ground for the blower motor is provided from the blower motor speed control. Ground is provided for the blower motor speed control. The HVAC module provides a blower target speed signal to the blower motor speed control to control the blower speed. The actual blower speed signal is provided to the HVAC module from the blower motor speed control.
- DTC B10AF:12 (Blower Fan Relay: Circuit Short to Battery)- The HVAC module senses voltage on the relay coil ground circuit when the relay is grounded by the HVAC module, indicating a short directly to voltage.
- DTC B10AF:13 (Blower Fan Relay: Circuit Open)- The HVAC 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 HVAC module senses no voltage on the blower motor control target speed signal circuit, indicating an open or a short directly 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
- Front Controls Interface Module (FCIM)
- 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 Q3.
For DTC B10B9:14, GO to Q5.
No
GO to Q2.
Q2 CHECK THE BLOWER MOTOR OPERATION USING ACTIVE COMMANDS
- Enter the following diagnostic mode on the scan tool: DataLogger- HVAC Module PID (Blower Motor Speed (BLOWRSPD)).
- Select PANEL mode on the HVAC controls.
- Select the lowest blower motor setting.
- Observe blower motor speed while using the scan tool to operate the HVAC module active command BLOWRSPD, increasing and decreasing the percentage value.
Does the blower motor speed change between low and high when the active command is changed?
Yes
INSTALL a new Front Controls Interface Module (FCIM). TEST the system for normal operation.
No
GO to Q8.
Q3 CHECK THE BLOWER MOTOR RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 1, circuit CBB93 (GY/BN) and ground.
Is the voltage greater than 10 volts?
Yes
GO to Q4.
No
VERIFY Battery Junction Box (BJB) fuse 93 (5A) is OK. If OK, REPAIR circuit CBB93 (GY/BN) 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.
Q4 CHECK THE BLOWER MOTOR RELAY COIL CONTROL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module- Electronic Manual Temperature Control (EMTC) C2357.
- Disconnect: HVAC Module- Dual Automatic Temperature Control (DATC) C228A.
- Measure the resistance between blower motor relay socket pin 2, circuit CH123 (VT/GN) and:
- For EMTC (Electronic Manual Temperature Control) systems, HVAC Module- EMTC (Electronic Manual Temperature Control) C2357-11, circuit CH123 (VT/GN), harness side.
- For DATC (Dual Automatic Temperature Control) systems, HVAC Module- DATC (Dual Automatic Temperature Control) C228A-11, circuit CH123 (VT/GN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to Q18.
No
REPAIR circuit CH123 (VT/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
Q5 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: HVAC Module- Electronic Manual Temperature Control (EMTC) C2357.
- Disconnect: HVAC Module- Dual Automatic Temperature Control (DATC) C228A.
- Disconnect: Blower Motor Speed Control C271.
- Measure the resistance between ground and blower motor speed control C271-1, circuit (RD), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to Q6.
No
REPAIR circuit VH101 (WH/VT)/(RD) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
Q6 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT AND THE BLOWER MOTOR SPEED CONTROL FEEDBACK CIRCUIT FOR A SHORT TOGETHER
- Ignition OFF.
- Measure the resistance between blower motor speed control C271-1, circuit (RD), harness side and blower motor speed control module C271-3, circuit (BN), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to Q7.
No
REPAIR circuit VH101 (WH/VT)/(RD) and CH102 (YE/BU)/(BN) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
Q7 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT FOR AN OPEN
- Measure the resistance between blower motor speed control C271-1, circuit (RD), harness side and:
- HVAC module- EMTC (Electronic Manual Temperature Control) C2357-1, circuit VH101 (WH/VT), harness side.
- HVAC module- DATC (Dual Automatic Temperature Control) C228A-1, circuit VH101 (WH/VT), harness side.
Are the resistances less than 5 ohms?
Yes
INSTALL a new blower motor speed control. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the DTC returns, GO to Q18.
No
REPAIR circuit VH101 (WH/VT)/(RD) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
Q8 CHECK THE HVAC MODULE BLOWER MOTOR RELAY 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 or equivalent. 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 OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Select PANEL mode.
- Connect a 12-volt test lamp between blower motor relay socket pin 1, circuit CBB93 (GY/BN) and socket pin 2, circuit CH123 (VT/GN).
Does the test lamp illuminate?
Yes
GO to Q9.
No
GO to Q18.
Q9 CHECK THE BLOWER MOTOR RELAY SWITCH CONTACT VOLTAGE CIRCUIT FOR AN OPEN
- Measure the voltage between blower motor relay socket pin 3, circuit SBB18 (YE/RD) and ground.
Is the voltage greater than 10 volts?
Yes
GO to Q10.
No
VERIFY Battery Junction Box (BJB) fuse 18 (40A) is OK. If OK, REPAIR circuit SBB18 (YE/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.
Q10 CHECK THE BLOWER MOTOR RELAY
- Connect a fused jumper between blower motor relay socket pin 3, circuit SBB18 (YE/RD) and blower motor relay socket pin 5, circuit CH402 (YE/GN).
Does the blower motor operate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to Q11.
Q11 CHECK THE BLOWER MOTOR SPEED CONTROL GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Measure the resistance between blower motor speed control C271-4, circuit (BK/RD), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to Q12.
No
REPAIR circuit GD115 (BK/GY)/(BK/RD) for an open. TEST the system for normal operation.
Q12 CHECK THE BLOWER MOTOR
- Connect: Blower Motor Relay.
- Ignition ON.
- Select PANEL mode.
- Connect a fused jumper between blower motor speed control C271-4, circuit (BK/RD), harness side and blower motor speed control C271-5, circuit (BU), harness side.
Does the blower motor operate?
Yes
GO to Q15.
No
GO to Q13.
Q13 CHECK THE BLOWER MOTOR VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Disconnect: Blower Motor C288.
- Measure the resistance between blower motor relay socket pin 5, circuit CH402 (YE/GN) and blower motor C288-2, circuit (BK), harness side.
Is the resistance less than 5 ohms?
Yes
GO to Q14.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
Q14 CHECK THE BLOWER MOTOR GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between blower motor C288-1, circuit (BU), harness side and blower motor speed control C271-5, circuit (BU), harness side.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor. TEST the system for normal operation.
No
REPAIR circuit (BU) for an open. TEST the system for normal operation.
Q15 CHECK THE BLOWER MOTOR SPEED CONTROL FEEDBACK CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module- EMTC (Electronic Manual Temperature Control) C2357.
- Disconnect: HVAC Module- DATC (Dual Automatic Temperature Control) C228A.
- Ignition ON.
- Measure the voltage between ground and blower motor speed control C271-3, circuit (BN), harness side.
Is any voltage present?
Yes
REPAIR circuit CH102 (YE/BU)/(BN) for a short to voltage. TEST the system for normal operation.
No
GO to Q16.
Q16 CHECK THE BLOWER MOTOR SPEED CONTROL FEEDBACK CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and blower motor speed control C271-3, circuit (BN), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to Q17.
No
REPAIR circuit CH102 (YE/BU)/(BN) for a short to ground. TEST the system for normal operation.
Q17 CHECK THE BLOWER MOTOR SPEED CONTROL FEEDBACK CIRCUIT FOR AN OPEN
- Measure the resistance between blower motor speed control C271-3, circuit (BN), harness side and:
- HVAC module- EMTC (Electronic Manual Temperature Control) C2357-14, circuit CH102 (YE/BU), harness side.
- HVAC module- DATC (Dual Automatic Temperature Control) C228A-14, circuit CH102 (YE/BU), harness side.
Are the resistances less than 5 ohms?
Yes
INSTALL a new blower motor speed control. TEST the system for normal operation. If the condition returns, GO to Q18.
No
REPAIR circuit CH102 (YE/BU)/(BN) for an open. TEST the system for normal operation.
Q18 CHECK THE HVAC MODULE CONNECTION
- Inspect the HVAC module component and harness side connectors for:
- corrosion
- damaged pins
- pushed-out terminals
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Enter the following diagnostic mode on the scan tool: Self-Test- HVAC Module.
- 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. TEST the system for normal operation.