Engine-Codes - Mercury - B12A4 MERCURY

B12A4 MERCURY - Mode Door Actuator Drive Circuit Shorted To Battery Voltage

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?

B12A4 MERCURY Possible Causes

  • Stuck or damaged linkage or door
  • Faulty Mode Door Actuator
  • Mode Door Actuator harness is open or shorted
  • Mode Door Actuator circuit poor electrical connection
  • Electronic Manual Temperature Control (EMTC) Module
  • Electronic Automatic Temperature Control (EATC) Module

How do I fix code B12A4 MERCURY

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Cost of diagnosing the B12A4 MERCURY code

Labor: 1.0

The cost of diagnosing the B12A4 MERCURY code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

B12A4 MERCURY Meaning

Under normal operation, to rotate the mode door actuator clockwise, the Electronic Manual Temperature Control (EMTC) or Electronic Automatic Temperature Control (EATC) module supplies voltage and ground to the floor/defrost/panel mode door actuator motor through the circuit. To rotate the mode door actuator counterclockwise, the EMTC module or EATC module reverses the voltage and ground circuits.
The mode door actuator feedback resistor is supplied a ground from the EMTC module or EATC module and a 5-volt reference voltage. The EMTC module or EATC module reads the voltage on the mode door actuator feedback circuit to determine the mode door actuator position by the position of the actuator feedback resistor wiper arm.

B12A4 MERCURY More Information

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