B3921 Buick Code - Group 2 Seat Motors Circuit Shorted
Quick Answer
The Seat Memory Control Module controls the seat, lumbar, and adjustable pedal motors via half bridges that are connected to power rails internal to the module. Common causes include Faulty Seat, Lumbar, or Adjustable Pedal Motors, Seat, Lumbar, or Adjustable Pedal Motors harness is open or shorted, Seat, Lumbar, or Adjustable Pedal Motors circuit poor electrical connection. 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
- B3921 Buick indicates Group 2 Seat Motors Circuit Shorted.
- Common causes
- Common causes include Faulty Seat, Lumbar, or Adjustable Pedal Motors, Seat, Lumbar, or Adjustable Pedal Motors harness is open or shorted, Seat, Lumbar, or Adjustable Pedal Motors circuit poor electrical connection.
- 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.
Code B3921 Buick Description
When a power seat, lumbar, or adjustable pedal switch is pressed or when a memory recall is requested, each seat motor receives battery voltage and ground from the seat memory control module via the motor control circuits. All motors are reversible, so the direction the motor rotates depends on which control circuit voltage is applied and which control circuit ground is applied. When the switch is operated in the opposite direction, the module reverses the polarity and applies voltage and ground to the opposite circuits to move the seat in the opposite direction.
The Diagnostic Trouble Code (DTC) sets when the voltage on any power rail 2 motor control circuit exceeds 2.78 volts for 100 ms or is below 1.47 volts for 100 ms.
What are the Possible Causes of the DTC B3921 Buick?
- Faulty Seat, Lumbar, or Adjustable Pedal Motors
- Seat, Lumbar, or Adjustable Pedal Motors harness is open or shorted
- Seat, Lumbar, or Adjustable Pedal Motors circuit poor electrical connection
How to Fix the DTC B3921 Buick?
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.
Code Tech Notes
B3921 02 Group 2 Seat Motors Circuit Shorted to Ground
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the B3921 Buick 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.
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Frequently Asked Questions about B3921 Buick Code
What does the OBDII code B3921 mean for a Buick?
This code indicates a short circuit in the Group 2 seat motors, which control specific seat adjustments.
What are the common symptoms of the B3921 code?
Symptoms include malfunctioning seat adjustments, inability to move the seat, or the seat being stuck in one position.
What causes the B3921 code to appear?
Common causes include damaged wiring, a short circuit in the seat motor, or a faulty seat adjustment control module.
How can I diagnose the B3921 code?
Inspect the wiring and connectors for damage or corrosion, test the seat motor for proper operation, and check for any electrical shorts.
Can I still drive my Buick with the B3921 code?
Yes, the code does not affect drivability, but seat adjustment functionality may be compromised.
How do I fix the B3921 code on my Buick?
Repairs typically involve replacing damaged wiring, repairing shorts, or replacing the seat motor if it's faulty.
Is the B3921 code related to passenger or driver seats?
It depends on the specific seat motor group experiencing the issue; refer to your vehicle's wiring diagram for clarification.
Will clearing the code fix the issue permanently?
No, clearing the code won't solve the underlying problem. The cause of the short circuit must be repaired.
How much does it cost to repair a B3921 code?
Costs vary based on the issue; wiring repairs may be inexpensive, but motor or module replacement can be more costly.
Can a faulty fuse cause the B3921 code?
While unlikely, a blown fuse may indicate a related electrical issue contributing to the short circuit.
Discuss the causes and fixes for B3921 Buick OBDII Code
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