Normal Operation

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

Under normal operation, when blower operation is requested a signal is sent from the control module to the Smart Junction Box (SJB) through circuit 1398 (PK/WH) (Single-zone EMTC only) or over the SCP BUS (Dual-zone EMTC only). The SJB sends a message over the SCP bus to the PCM.

The blower motor relay coil receives ignition voltage through circuit 298 (VT/OG). The coil receives ground from the Smart Junction Box (SJB) through circuit 1322 (BN/WH) 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 371 (PK/WH). Ground for the blower motor is provided through circuit 261 (OG/BK) from the blower resistor or the blower switch (HI). The blower resistor and blower switch is grounded through circuit 1205 (BK).