Test M: The Blower Motor Is Inoperative - EATC

PINPOINT TEST M: THE BLOWER MOTOR IS INOPERATIVE - EATC

M1-M3:

M3-M5:

M6-M8:

M8-M10:

M10-M12:

M12-M13:

Normal Operation
Under normal operation, the blower motor relay coil receives ground through circuit 296 (WH/VT)/57 (BK). The coil receives voltage from the electronic automatic temperature control (EATC) module through circuit 399 (BN/YE) if any position but OFF is selected. Voltage is supplied to the relay switch contact through circuit 364 (BK/LG). When the relay coil is energized, voltage is delivered to the blower motor through circuit 181 (BN/OG). Ground for the motor is provided through circuit 261 (OG/BK) from the blower control module. Ground for the blower control module is provided by circuit 57 (BK).

The blower motor control module receives a 1-2 volt signal from the EATC module through circuit 754 (LG/WH) to determine the desired blower motor speed. The EATC module receives a feedback voltage from the blower motor control module through circuit 752 (YE/RD) to determine actual blower motor speed. When the highest blower motor setting is selected, the EATC module sends 12 volts to the blower control module through circuit 261 (OG/BK)/751 (DB/WH).

Possible Causes
- An open in circuits 57 (BK), 181 (BN/OG), 261 (OG/BK), 296 (WH/VT), 399 (BN/YE) or 751 (DB/WH)
- A short to ground in circuit 261 (OG/BK), 399 (BN/YE) or 751 (DB/WH)
- Blower motor
- Blower motor relay
- Blower motor control module
- Electronic automatic temperature control (EATC) module