B1991 Mercury Code - Pedal Forward / Rearward Potentiometer Feedback Circuit Short to Battery
Quick Answer
The B1991 diagnostic trouble code (DTC) for Mercury vehicles indicates a problem with the pedal forward/rearward potentiometer feedback circuit being shorted to the battery. Common causes include Wiring harness damage or corrosion, Faulty pedal position sensor, Short circuit in the potentiometer feedback circuit. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- B1991 Mercury indicates Pedal Forward / Rearward Potentiometer Feedback Circuit Short to Battery.
- Common causes
- Common causes include Wiring harness damage or corrosion, Faulty pedal position sensor, Short circuit in the potentiometer feedback circuit.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code B1991 Mercury Description
The B1991 diagnostic trouble code (DTC) for Mercury vehicles indicates a problem with the pedal forward/rearward potentiometer feedback circuit being shorted to the battery. This code is typically associated with electronic throttle control systems, where the pedal position sensor sends signals to the engine control module (ECM) to adjust throttle opening. The potentiometer in the pedal assembly measures the pedal's position and sends feedback to the ECM. A short to battery in this circuit means that there is an unintended connection between the potentiometer feedback wire and the vehicle's battery power supply.
Common Causes of B1991 Mercury
- Wiring harness damage or corrosion
- Faulty pedal position sensor
- Short circuit in the potentiometer feedback circuit
- ECM malfunction
- Battery voltage fluctuations
Symptoms of B1991 Mercury
- Erratic throttle response
- Loss of throttle control
- Poor acceleration
- Stalling
- Check Engine Light illuminated
How to Fix B1991 Mercury
- Begin by conducting a visual inspection of the wiring harness connected to the pedal position sensor to check for any signs of damage or corrosion.
- Test the pedal position sensor using a multimeter to ensure it is functioning correctly.
- Check for any short circuits in the potentiometer feedback circuit by performing a continuity test.
- If no issues are found with the sensor or wiring, diagnose the ECM for any faults or reprogram it if necessary.
- Clear the DTC using a scan tool and test drive the vehicle to confirm that the issue has been resolved.
Cost to Fix B1991 Mercury
The typical repair costs for addressing a B1991 code can vary depending on the specific cause of the issue. On average, the parts required for this repair, such as a new pedal position sensor or ECM reprogramming, can range from $100 to $300. Labor costs at auto repair shops typically fall between $80 and $150 per hour, with the total repair bill likely to be in the range of $200 to $500. It is advisable to consult with a local auto repair shop for a more accurate estimate based on your vehicle make and model, as well as the extent of the necessary repairs.
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Frequently Asked Questions about B1991 Mercury Code
1. What are the common symptoms of OBDII code B1991 in a Mercury related to the Pedal Forward/Rearward Potentiometer Feedback Circuit Short to Battery?
The common symptoms include erratic throttle response, sudden loss of throttle control, and possibly triggering the vehicle into limp mode.
2. What are the possible causes of OBDII code B1991 in a Mercury?
Possible causes include wiring issues, a faulty pedal position sensor, a short circuit to the battery, or a malfunctioning electronic control unit (ECU).
3. How can I diagnose the source of the Pedal Forward/Rearward Potentiometer Feedback Circuit Short to Battery issue in my Mercury?
You can start by conducting a visual inspection of the wiring, connectors, and sensors involved. Using a multimeter to test for continuity and resistance can help pinpoint the faulty component.
4. Can I drive my Mercury with OBDII code B1991 present?
It is not recommended to drive your vehicle with this code present, as it can lead to unsafe driving conditions due to erratic throttle behavior.
5. Are there any temporary fixes for OBDII code B1991 in a Mercury?
Temporary fixes such as clearing the code with an OBDII scanner may temporarily resolve the issue, but it is crucial to address the root cause to prevent further problems.
6. How much does it typically cost to repair OBDII code B1991 in a Mercury at a mechanic?
The cost of repair can vary depending on the exact cause of the issue, but it typically ranges from $100 to $500, including parts and labor.
7. Can I reset OBDII code B1991 in my Mercury without fixing the underlying issue?
While you can reset the code using an OBDII scanner, it is not recommended as the issue will likely resurface, potentially causing further damage.
8. Is OBDII code B1991 a common problem in Mercury vehicles?
While not extremely common, this code can occur in Mercury vehicles, especially in models equipped with electronic throttle control systems.
9. Will OBDII code B1991 cause my Mercury to fail an emissions test?
Yes, having this code present can cause your Mercury to fail an emissions test, as it indicates a potential issue with the throttle control system.
10. How long does it typically take to repair OBDII code B1991 in a Mercury?
The repair time can vary depending on the exact cause and complexity of the issue, but it usually takes a few hours to a full day for a professional mechanic to diagnose and fix the problem.
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