B1991 — Pedal Forward / Rearward Potentiometer Feedback Circuit Short to Battery #

Note: The definition of DTC B1991 may vary depending on the vehicle’s manufacturer (OEM). Always refer to your OEM service documentation for the most accurate description for your specific vehicle.

• Ford: Pedal Forward/Rearward Potentiometer Feedback Circuit Short to Battery
• Jaguar: Pedal Position Feedback Circuit Short to Power
• Land Rover: Pedal Adjust Feedback Sensor Circuit Short to Battery

Code Summary for B1991 #

The Diagnostic Trouble Code (DTC) B1991 indicates that the vehicle’s control module has detected a short circuit to battery voltage in the pedal forward/rearward potentiometer feedback circuit. In simple terms, this means the electrical signal from the pedal adjustment sensor (potentiometer) is showing an unexpected high voltage, likely due to a wiring or component fault. This sensor monitors the position of the adjustable pedal assembly, ensuring it communicates its position accurately to the vehicle’s control system. When this circuit is compromised, the system cannot reliably determine the pedal position, potentially affecting pedal adjustment functions and safety features. This code is typically found on vehicles equipped with adjustable pedals, a luxury or ergonomic feature allowing drivers to move pedals forward or backward for comfort.

Common Symptoms for Code B1991 #

When B1991 is active, you’ll likely notice issues related to pedal adjustment. These symptoms are often subtle unless the pedal adjustment function is used regularly. Here’s what you might observe:

• Adjustable pedals do not respond to switch input
• Pedal adjustment switch may be inoperative or intermittent
• “Adjustable Pedal Fault” warning lamp or message on the dashboard
• Pedal movement stops mid-adjustment or feels erratic
• In rare cases, memory seat or pedal functions may be disabled
• No change in pedal position even though the motor can be heard operating

Most Likely Causes for B1991 #

The B1991 code is usually triggered by an electrical problem between the pedal position potentiometer and the vehicle’s control module. Some causes are more common than others. Here they are, in order of likelihood:

1. Damaged or shorted wiring harness—especially if the harness is pinched under the seat or near the pedal assembly.
2. Faulty pedal position potentiometer (sensor)—the sensor itself may have internal faults causing a short to voltage.
3. Corroded or disconnected connectors—moisture intrusion or loose pins can cause electrical shorts.
4. Incorrectly performed electrical repairs—aftermarket wiring, splices, or repairs not meeting OEM standards.
5. Control module (ECU/BCM) fault—rare, but possible if all other components check out.

Step-by-Step Diagnostic Guide for B1991 #

Diagnosing B1991 should be methodical to avoid unnecessary part replacements. Here’s a structured approach:

• 1. Verify the code: Use an OBD-II/EOBD scan tool to confirm B1991 is active and record freeze frame data.
• 2. Visual inspection: Check the pedal adjustment system wiring and connectors for obvious damage, corrosion, or loose connections.
• 3. Check for technical service bulletins (TSBs): Some manufacturers issue TSBs for recurring issues—review OEM literature for updates.
• 4. Test pedal potentiometer voltage: Using a multimeter, measure the voltage at the potentiometer sensor. A short to battery will show full battery voltage (typically 12V) where there should be a variable signal (usually 0.5–5V reference).
• 5. Inspect wiring harness: Trace the harness from the pedal assembly to the control module, looking for pinched, frayed, or abraded wires.
• 6. Check connectors: Unplug, clean, and reseat all connectors related to the pedal adjustment circuit. Look for bent pins or water intrusion.
• 7. Substitute known-good parts: If possible, swap the pedal potentiometer or control module with a verified working unit to isolate the fault.
• 8. Clear the code and retest: After repairs, clear the code and operate the pedal adjustment system to see if the DTC returns.

Possible Repairs for B1991 #

The right repair depends on the root cause found during diagnosis. Here are the most common fixes linked to the causes above:

• Repair or replace damaged wiring harness—remove sections of harness with exposed or shorted wires, and splice in new wiring following OEM repair standards.
• Replace the pedal position potentiometer—if the sensor is faulty or internally shorted, install a new OEM or equivalent sensor.
• Clean or replace corroded connectors—remove oxidation, dry out connectors, and apply dielectric grease before reconnecting. Replace connectors if pins are broken or too corroded.
• Correct previous wiring errors—undo improper splices or connections, and restore to OEM specifications.
• Replace the control module—only after confirming all other components are functional, as this is rare and expensive.

Is It Safe to Drive with Code B1991? #

Limited—In most cases, B1991 does not directly affect the vehicle’s ability to drive, since it’s related to the comfort feature of adjustable pedals. However, if your vehicle shares pedal position data with safety systems or memory seat functions, those may be impaired. If pedal adjustment is stuck in an uncomfortable or unsafe position, avoid driving until the repair is made.

Vehicles Most Commonly Affected by B1991 #

You’ll typically find B1991 on vehicles with electrically adjustable pedals, a feature more common on higher-end models or certain OEMs. Some vehicles known for this code include:

• Ford F-Series trucks (F-150, F-250, etc., 2000s–2010s)
• Ford Expedition, Explorer, and Flex
• Lincoln Navigator and Aviator
• Jaguar XJ and XF (with memory seat/pedal systems)
• Land Rover Range Rover (select models)
• Chrysler minivans and luxury SUVs (select years with adjustable pedals)

Common Mistakes & Best Practices with B1991 #

When troubleshooting B1991, avoid these pitfalls and follow these tips for success:

• Don’t replace the pedal potentiometer without first checking wiring integrity—wiring faults are more common.
• Never assume the control module is faulty before verifying all related circuits and components.
• Use only OEM or equivalent parts for sensor and connector replacements to ensure compatibility.
• Don’t overlook TSBs or OEM wiring diagrams—they often contain crucial information.
• Always disconnect the battery before repairing wiring to avoid accidental shorts or module damage.

Quick FAQ on B1991 #

Here are answers to some of the most common questions about B1991:

• Q: Will B1991 trigger the Check Engine Light?
  A: Usually no—the Check Engine Light is for powertrain codes, but you may see a specific warning light or message related to adjustable pedals or body electronics.
• Q: Can I adjust the pedals manually if B1991 is present?
  A: If the code is active, the motorized adjustment is likely disabled as a safety precaution. Manual adjustment is generally not possible unless designed as a backup.