B3921 GMC 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 GMC 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 GMC 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 GMC?
- 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 GMC?
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 GMC 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 GMC Code
1. What are the common symptoms of OBDII code B3921 GMC?
The common symptoms of OBDII code B3921 GMC, Group 2 Seat Motors Circuit Shorted, may include non-functioning or erratic movement of the affected seat motors.
2. What can cause the Group 2 Seat Motors Circuit Shorted code B3921 in a GMC vehicle?
This code can be caused by issues such as a short circuit in the wiring, a faulty seat motor, or a malfunctioning control module.
3. How can I diagnose the Group 2 Seat Motors Circuit Shorted code B3921 in my GMC?
Diagnosing this code typically involves checking the wiring harness for shorts, testing the seat motors for proper functionality, and inspecting the control module for any faults.
4. Is it safe to drive my GMC with the B3921 OBDII code triggered?
It is generally safe to drive your GMC with the B3921 code triggered, but it is recommended to address the issue promptly to avoid any inconvenience or potential safety concerns.
5. Can I repair the Group 2 Seat Motors Circuit Shorted code B3921 in my GMC myself?
Depending on your level of automotive expertise, you may be able to repair the B3921 code yourself by identifying and fixing the underlying cause, such as repairing a wiring short or replacing a faulty seat motor.
6. Will resetting the OBDII system clear the B3921 GMC trouble code?
Resetting the OBDII system may temporarily clear the B3921 trouble code, but if the underlying issue is not addressed, the code is likely to reappear upon further driving.
7. How much does it typically cost to repair the Group 2 Seat Motors Circuit Shorted code B3921 in a GMC?
The cost of repairing the B3921 code can vary depending on the specific cause of the issue, but it may involve expenses for parts replacement, labor, and diagnostic services.
8. Are there any preventive measures to avoid triggering the B3921 OBDII code in my GMC?
To prevent the B3921 code from being triggered, you can perform regular inspections of the seat motors and wiring harness, ensuring they are in good condition and free from any damage or wear.
9. Can a faulty control module cause the B3921 GMC trouble code?
Yes, a faulty control module can be one of the potential causes of the B3921 trouble code, as it may affect the operation of the seat motors and lead to circuit shorts.
10. How urgent is it to address the Group 2 Seat Motors Circuit Shorted code B3921 in a GMC?
While it is not typically an emergency situation, addressing the B3921 code promptly is recommended to prevent further damage to the seat motors or electrical system of the vehicle.
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