B3921 Cadillac 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 Cadillac 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 Cadillac 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 Cadillac?
- 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 Cadillac?
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 Cadillac 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 Cadillac Code
1. What does the OBDII code B3921 mean for a Cadillac?
Code B3921 indicates a short circuit in the Group 2 Seat Motors Circuit, which controls specific seat adjustment functions.
2. What are common symptoms of the B3921 code?
Symptoms may include non-functional seat adjustments, unusual noises from the seat motors, or intermittent operation of the affected seat functions.
3. What causes the B3921 code to appear?
Common causes include damaged wiring, a short circuit in the seat motor circuit, a faulty seat adjustment motor, or a malfunctioning seat control module.
4. How can I diagnose the B3921 code?
Start by inspecting the wiring and connectors for damage or corrosion, then test the seat motors and seat control module for proper operation.
5. Can I still drive my Cadillac with a B3921 code?
Yes, the code does not affect drivability, but seat adjustment functions may be limited or non-functional.
6. How do I fix the B3921 code on my Cadillac?
Repairs may involve replacing damaged wiring, the seat adjustment motor, or the seat control module, depending on the root cause.
7. Is the B3921 code related to all seat motors in the vehicle?
No, it specifically pertains to the Group 2 Seat Motors Circuit, which controls certain seat functions.
8. How much does it typically cost to repair the B3921 code?
Repair costs vary, but they can range from $100 to $500 depending on whether wiring, motors, or modules need replacement.
9. Can a blown fuse cause the B3921 code?
While less common, a blown fuse in the seat motor circuit could contribute to the issue and should be checked during diagnosis.
10. Do I need professional help to resolve the B3921 code?
If you're experienced with electrical systems, you may be able to fix minor wiring issues yourself, but complex repairs may require a professional.
Discuss the causes and fixes for B3921 Cadillac OBDII Code
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