B1991: Pedal Position Sensor Short to Battery
The B1991 code indicates that the Seat Control Module (SCM) has detected an abnormally high voltage on the pedal position potentiometer feedback circuit, specifically a short to battery positive (B+). This potentiometer is part of the power pedal adjustment system and provides a variable voltage signal representing the pedal's fore/aft position. When the feedback circuit is shorted to B+, the SCM receives a constant maximum voltage, preventing it from determining the actual pedal position. This can disable automatic adjustment and memory seat functions.
1. Commonly Affected Makes
2. Most Common Causes
- Feedback circuit wiring shorted to battery positive (B+)
- Internally damaged pedal potentiometer with leakage to the power terminal
- Corroded, bent, or moisture-contaminated pins in the potentiometer or SCM connector causing a short
- Damaged input circuit in the Seat Control Module (SCM)
- Incorrect fuse or previous electrical modification in the seat circuit
3. Symptoms You Will Notice
- Power pedals inoperative or stuck in one position
- Memory seat/pedal functions not working or not saving positions
4. Step-by-Step Diagnosis
Scan for codes and verify B1991 is present
Visually inspect pedal potentiometer connector and SCM connector for damage, corrosion, or bent pins
Measure voltage on the feedback circuit; if near battery voltage with pedal moved, suspect short to B+
Disconnect potentiometer; if voltage drops, replace potentiometer; if not, check wiring for short to B+
If wiring and potentiometer are good, test SCM by substitution or further diagnostics
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but the power pedals may not adjust properly, which could affect driving comfort and memory settings.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the issue is a simple wiring repair or requires replacing the pedal potentiometer or SCM.