Normal Operation
Under normal operation, the blower motor relay coil receives a ground from the HVAC module through circuit CH123 (VT/GN). The coil receives ignition voltage through circuit CBP45 (YE). Voltage is supplied to the relay switch contact through circuit SBB35 (BU/RD). When the relay coil is energized, voltage is delivered to the blower motor speed control through circuit CH402 (YE/GN). Ground for the blower motor speed control is provided by circuit GD115 (BK/GY). Voltage for the motor is provided through circuit VH301 (YE/BU) from the blower motor speed control. Ground for the motor is provided through circuit VH219 (GY) from the blower motor speed control. The HVAC module sends a Pulse-Width Modulation (PWM) signal to the blower motor speed control through circuit VH101 (WH/VT) to control the blower speed.
| DTC Description | Fault Trigger Conditions |
|---|---|
|
The module senses excessive voltage on the relay coil ground circuit, indicating a short directly to voltage. |
|
The module senses no voltage on the relay coil ground circuit, indicating an open or a short directly to ground. |
|
The module senses excessive voltage on the blower motor control PWM circuit, indicating a short directly to voltage. |
|
The module senses no voltage on the blower motor control PWM 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 - Dual Automatic Temperature Control (DATC)
- Blower motor
Under normal operation, the blower motor relay coil receives a ground from the HVAC module through circuit CH123 (VT/GN). The coil receives ignition voltage through circuit CBP45 (YE). Voltage is supplied to the relay switch contact through circuit SBB06 (BN/RD). When the relay coil is energized, voltage is delivered to the blower motor speed control through circuit CH402 (YE/GN). Ground for the blower motor speed control is provided by circuit GD115 (BK/GY). Voltage for the motor is provided through circuit VH301 (YE/BU) from the blower motor speed control. Ground for the motor is provided through circuit VH219 (GY) from the blower motor speed control. The HVAC module sends a Pulse-Width Modulation (PWM) signal to the blower motor speed control through circuit VH101 (WH/VT) to control the blower speed.
- DTC B10AF:14 (Blower Fan Relay: Circuit Short to Ground or Open) - The module senses no voltage on the relay coil ground circuit, indicating an open or a short directly to ground.
- DTC B10B9:14 (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 directly to ground.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Blower motor speed control
- HVAC module - Dual Automatic Temperature Control (DATC)