B3921 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 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 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?
- 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?
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 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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Information for Specific Makes
- B3921 Buick — Group 2 Seat Motors Circuit Shorted
- B3921 Cadillac — Group 2 Seat Motors Circuit Shorted
- B3921 Chevrolet — Group 2 Seat Motors Circuit Shorted
- B3921 GMC — Group 2 Seat Motors Circuit Shorted
- B3921 Pontiac — Group 2 Seat Motors Circuit Shorted
- B3921 Saturn — Group 2 Seat Motors Circuit Shorted
Frequently Asked Questions about B3921 Code
1. What are the common symptoms of OBDII code B3921 - Group 2 Seat Motors Circuit Shorted?
- Common symptoms include non-functioning seat motors in group 2, such as seat adjustment issues or lack of movement.
2. What can cause the OBDII code B3921 to trigger?
- The code B3921 is triggered when there is a short circuit detected in the circuit of group 2 seat motors.
3. How can I diagnose the issue related to OBDII code B3921?
- Diagnosis involves checking the wiring and connections related to group 2 seat motors, as well as inspecting the motors themselves for any visible damage.
4. What are some possible repair tips for resolving OBDII code B3921?
- Repair tips may include repairing or replacing damaged wiring, connectors, or seat motors in group 2 as necessary to resolve the short circuit issue.
5. Can I reset the OBDII code B3921 without fixing the underlying problem?
- While you can clear the code temporarily, it is important to address the root cause of the short circuit to prevent the code from reoccurring.
6. Are there any safety concerns associated with OBDII code B3921?
- Depending on the specific symptoms, safety concerns may arise if the seat motors are not functioning correctly, potentially affecting the driver's ability to adjust their seat position.
7. Is it possible to drive the vehicle with OBDII code B3921 present?
- It is generally not recommended to drive the vehicle with unresolved OBDII codes, as they may indicate underlying issues that could impact the vehicle's performance or safety.
8. How can I prevent OBDII code B3921 from occurring in the future?
- Regularly inspecting and maintaining the wiring and components related to the seat motors can help prevent short circuits that trigger the B3921 code.
9. Can a DIY enthusiast repair OBDII code B3921, or is professional assistance recommended?
- Depending on your experience and comfort level with automotive repairs, you may be able to address the issue yourself by following repair guides or seeking guidance from professionals.
10. Does OBDII code B3921 affect the vehicle's overall performance?
- While the B3921 code itself may not directly impact performance, addressing the underlying short circuit issue promptly is important to maintain the vehicle's electrical system integrity.
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