B1990 — Pedal Forward / Rearward Potentiometer Feedback Circuit Failure #

Please note: The wording of this DTC (Diagnostic Trouble Code) may vary depending on the manufacturer. Always refer to OEM (Original Equipment Manufacturer) documentation for your specific vehicle.

Known label variations for B1990:

• Ford: Pedal Forward / Rearward Potentiometer Feedback Circuit Failure
• Jaguar: Pedal Adjuster Position Sensor Circuit Failure
• Lincoln: Adjustable Pedal Position Sensor Circuit Malfunction
• Mazda: Accelerator Pedal Position Sensor Range/Performance

Summary of the B1990 Code #

B1990 is an OBD-II (On-Board Diagnostics II) trouble code indicating a problem within the feedback circuit of the mechanism that controls the adjustable pedal position—specifically, the potentiometer that senses the forward and rearward movement of the pedal assembly. A potentiometer is a variable resistor acting as a position sensor, converting pedal movement into an electrical signal that the vehicle’s control module can interpret. When the circuit fails, the vehicle cannot accurately detect or control the pedal adjustment, potentially affecting both comfort and, in rare cases, drivability. This code is flagged when the control module detects a voltage or resistance value outside the expected range during pedal adjustment. While most drivers will notice a loss of pedal adjustment capability, other symptoms may also be present depending on the vehicle.

Common Symptoms for Code B1990 #

When B1990 is stored, your vehicle may display several noticeable symptoms. Most are related to the electronic adjustable pedal system, but depending on the design, other comfort or safety functions might be impacted. Here’s what you might experience:

• Pedal adjustment function is inoperative—the pedals do not move when the adjust switch is activated.
• Warning lights or messages—a dashboard warning or “adjustable pedal fault” message may appear.
• Unusual pedal positions—pedals may be stuck in an uncomfortable position and cannot be moved.
• In rare cases, memory seat/pedal functions may not sync or operate correctly.
• Possible clicking or buzzing sounds from under the dash when attempting adjustment.

Most Likely Causes for Code B1990 #

The root cause of B1990 is typically electrical, but mechanical faults in the pedal assembly can also trigger this code. Here are the most common reasons, listed in order of likelihood:

1. Faulty pedal position potentiometer (sensor failure, internal open/short, or excessive wear)
2. Damaged or corroded wiring/connectors in the pedal feedback circuit
3. Faulty pedal adjustment motor (if the sensor is integrated)
4. Blown fuse or faulty relay for the pedal adjustment system
5. Faulty or misconfigured control module (rare)
6. Mechanical obstruction preventing the pedal from moving, causing abnormal sensor readings

Step-by-Step Diagnostic for B1990 #

A systematic approach helps isolate the cause of B1990 and prevents unnecessary parts replacement. Always use OEM wiring diagrams and follow safety protocols.

• Step 1: Confirm the DTC presence. Use a compatible scan tool to verify B1990 and check for related codes (especially those related to pedal or seat modules).
• Step 2: Visual inspection. Check the pedal assembly, wiring harness, connectors, and the potentiometer for visible signs of damage, corrosion, or loose connections.
• Step 3: Check fuses and relays. Inspect and test the fuses and relays associated with the adjustable pedal system.
• Step 4: Test the potentiometer. Using a multimeter, measure resistance or voltage at the potentiometer terminals while moving the pedal adjustment switch. Look for smooth changes without dropouts or spikes.
• Step 5: Inspect wiring continuity. Perform continuity and short-to-ground checks on the wiring between the potentiometer and control module.
• Step 6: Check for mechanical obstruction. Manually inspect the pedal movement for blockage or restriction.
• Step 7: If all else checks out, test/replace the control module as per OEM procedure.

Possible Repairs for Code B1990 #

Based on the diagnostic findings, the following repairs are most effective for resolving B1990. Always verify the repair by clearing the code and retesting the system.

• Replace the pedal position potentiometer if found faulty or worn.
• Repair or replace damaged wiring or connectors in the feedback circuit.
• Replace the pedal adjustment motor if it includes the integrated sensor and fails testing.
• Replace blown fuses or faulty relays linked to the pedal adjustment system.
• Remove mechanical obstructions and realign the pedal assembly if necessary.
• Reprogram or replace the control module only if all other components test good and the code persists (rare scenario).

Can You Drive with Code B1990? #

Yes, you can generally drive with code B1990 present, because this fault almost always affects only the comfort or convenience of pedal adjustment—not core drivability or safety features. However, if the pedal is stuck in a position that makes it difficult to operate the vehicle safely (especially for shorter or taller drivers), have the issue addressed as soon as possible. If warning lights for other systems appear alongside B1990, further diagnosis is recommended.

Vehicles Most Commonly Affected by B1990 #

B1990 is most frequently encountered on vehicles equipped with electrically adjustable pedals, a feature more common in certain brands and luxury models. Here are some vehicle lines where this code is regularly seen:

• Ford F-Series trucks (F-150, F-250, F-350)
• Lincoln Navigator, Lincoln Town Car
• Ford Expedition
• Jaguar S-Type, Jaguar XJ
• Mazda MPV (with adjustable pedals)
• Mercury Grand Marquis

Other brands may use similar pedal adjustment systems, but these are the most commonly reported in technical bulletins and repair databases.

Common Mistakes & Best Practices for B1990 #

Missteps in diagnosing B1990 can lead to wasted time and unnecessary parts replacement. Here’s how to avoid common pitfalls:

• Do not replace the pedal assembly before testing the potentiometer and wiring. Sensor or wiring faults are more common than complete assembly failures.
• Do not ignore corrosion or loose connections, especially in vehicles exposed to moisture or road salt.
• Always check for blown fuses or relays before assuming an electronic failure.
• Use OEM wiring diagrams to ensure accurate diagnosis.
• After repairs, clear the code and perform a system reset to confirm the fix.

Express FAQ for Code B1990 #

Still have questions about B1990? Here are quick answers to the most common concerns:

• Q: Will B1990 affect my cruise control or throttle response?
  A: No, B1990 specifically relates to pedal adjustment, not throttle control. Throttle and cruise systems use different sensors.
• Q: Can B1990 be triggered by a dead battery or after jump-starting?
  A: Rarely. While low voltage can cause unusual codes, B1990 almost always points to an actual circuit or sensor issue. If the code returns after clearing, follow normal diagnostic steps.

For best results, always consult your service manual or an experienced technician familiar with your vehicle’s adjustable pedal system. Early intervention ensures both comfort and long-term reliability.