AutoCodes – Mercury – B12B2 Mercury

B12B2 Mercury Code - Front Blower Motor PWM Drive Circuit Open or Shorted to Ground

Quick Answer

Under normal operation, the blower motor relay coil receives ignition voltage through the circuit. Common causes include Faulty Front Blower Motor Fuse, Faulty Front Blower Motor Relay, Front Blower Motor Relay harness is open or shorted. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: B12B2 Mercury indicates Front Blower Motor PWM Drive Circuit Open or Shorted to Ground.
Common causes: Common causes include Faulty Front Blower Motor Fuse, Faulty Front Blower Motor Relay, Front Blower Motor Relay harness is open or shorted.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 1,218

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 29, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B12B2 Mercury Description

Under normal operation, the blower motor relay coil receives ignition voltage through the circuit. The coil receives ground from the Electronic Manual Temperature Control (EMTC) Module through the circuit if any function selector position but OFF is selected. Voltage is supplied to the relay switch contact. When the relay coil is energized, the voltage is delivered to the blower motor through the circuit. Ground for the blower motor is provided through the circuit from the blower resistor or the blower switch (HI). The blower resistor and blower switch are grounded through the circuit. The module senses no voltage on the blower motor control Pulse Width Modulation (PWM) circuit, indicating an open or a short directly to ground.

OBDII Code B12B2 Mercury - Front Blower Motor PWM Drive Circuit Open or Shorted to Ground - AutoCodes.com — B12B2 Mercury Code - Front Blower Motor PWM Drive Circuit Open or Shorted to Ground

What does this mean?

What are the Possible Causes of the DTC B12B2 Mercury?

Faulty Front Blower Motor Fuse
Faulty Front Blower Motor Relay
Front Blower Motor Relay harness is open or shorted
Front Blower Motor Relay circuit poor electrical connection
Faulty Front Blower Motor
Faulty Electronic Manual Temperature Control (EMTC) Module

How to Fix the DTC B12B2 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B12B2 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B12B2 Mercury code?

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Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B12B2 Mercury Code

1. What are the common symptoms of OBDII code B12B2 for a Mercury with the title "Front Blower Motor PWM Drive Circuit Open or Shorted to Ground"?

- Common symptoms include the front blower motor not working at all or only working intermittently, no air coming out of the vents, or the blower motor operating at full speed regardless of settings.

2. What are the possible causes of the OBDII code B12B2 for a Mercury related to the front blower motor PWM drive circuit?

- Possible causes include a faulty blower motor resistor, damaged wiring or connectors in the PWM circuit, a blown fuse, or a malfunctioning blower motor control module.

3. How can I diagnose the OBDII code B12B2 on my Mercury indicating a front blower motor PWM drive circuit issue?

- Diagnosis typically involves checking the condition of the blower motor resistor, inspecting the wiring and connectors for any damage, testing the blower motor control module, and verifying the integrity of related fuses.

4. What are some repair tips for addressing OBDII code B12B2 on a Mercury for the front blower motor PWM drive circuit issue?

- Repair tips include replacing a faulty blower motor resistor, repairing or replacing damaged wiring or connectors, resetting the blower motor control module, and ensuring all related fuses are in good working order.

5. Can I continue driving my Mercury with the OBDII code B12B2 indicating a front blower motor PWM drive circuit problem?

- It is not recommended to continue driving the vehicle with this issue, as it can lead to discomfort due to lack of heating, defrosting, or cooling capabilities. It is best to address the problem promptly.

6. Is it possible to reset the OBDII code B12B2 on my Mercury after fixing the front blower motor PWM drive circuit issue?

- Yes, once the underlying problem causing the code has been resolved, you can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes.

7. How much does it typically cost to repair the front blower motor PWM drive circuit issue related to OBDII code B12B2 on a Mercury?

- The cost of repairs can vary depending on the exact cause of the issue and the labor rates in your area. It could range from a simple fuse replacement to a more involved repair involving components like the blower motor resistor or control module.

8. Are there any preventive measures I can take to avoid encountering OBDII code B12B2 on my Mercury in the future?

- Regularly inspecting the condition of the blower motor system, addressing any unusual noises or behaviors promptly, and ensuring proper maintenance of the HVAC system can help prevent issues leading to this OBDII code.