Pinpoint Test R: The Blower Motor Does Not Operate Correctly
Climate Control System
Pinpoint Test R: The Blower Motor Does Not Operate Correctly
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 B10B9:12 (Blower Control: Circuit Short to Battery)- The HVAC module senses excessive voltage on the blower motor control target speed signal circuit, indicating a short directly to voltage.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor speed control
- HVAC module
- Front Controls Interface Module (FCIM)
PINPOINT TEST R : THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY
R1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- Check the HVAC module for DTCs.
Is DTC B10B9:12 present?
Yes
GO to R2.
No
GO to R3.
R2 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT FOR A SHORT TO VOLTAGE
- 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.
- Ignition ON.
- Measure the voltage between ground and blower motor speed control C271-1, circuit (RD), harness side.
Is any voltage present?
Yes
REPAIR circuit VH101 (WH/VT)/(RD) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to R11.
R3 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 R4.
R4 CHECK THE BLOWER MOTOR RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Disconnect: HVAC Module- Electronic Manual Temperature Control (EMTC) C2357.
- Disconnect: HVAC Module- Dual Automatic Temperature Control (DATC) C228A.
- Measure the resistance between ground and blower motor relay socket pin 2, circuit CH123 (VT/GN) and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to R5.
No
REPAIR circuit CH123 (VT/GN) for a short to ground. TEST the system for normal operation.
R5 CHECK THE BLOWER MOTOR VOLTAGE CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Blower Motor C288.
- Ignition ON.
- Measure the voltage between ground and blower motor C288-2, circuit (BK), harness side.
Is any voltage present?
Yes
REPAIR circuit CH402 (YE/GN)/(BK) for a short to voltage. TEST the system for normal operation.
No
GO to R6.
R6 CHECK THE BLOWER MOTOR GROUND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Speed Control C271.
- Measure the resistance between ground and blower motor speed control C271-5, circuit (BU), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to R7.
No
REPAIR circuit (BU) for a short to ground. TEST the system for normal operation.
R7 CHECK THE BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT AND THE BLOWER MOTOR SPEED CONTROL FEEDBACK CIRCUIT FOR A SHORT TOGETHER
- Measure the resistance between blower motor speed control C271-1, circuit (RD), harness side and blower motor speed control C271-3, circuit (BN), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to R8.
No
REPAIR circuit VH101 (WH/VT)/(RD) or CH102 (YE/BU)/(BN) for a short together. TEST the system for normal operation.
R8 CHECK THE BLOWER MOTOR SPEED CONTROL FEEDBACK CIRCUIT FOR A SHORT TO VOLTAGE
- 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 R9.
R9 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.
Are the resistances greater than 10,000 ohms?
Yes
GO to R10.
No
REPAIR circuit CH102 (YE/BU)/(BN) for a short to ground. TEST the system for normal operation.
R10 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.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor speed control. TEST the system for normal operation. If the condition returns, GO to R11.
No
REPAIR circuit CH102 (YE/BU)/(BN) for an open. TEST the system for normal operation.
R11 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.