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AutoCodes - Generic - B3921

B3921 Code - Group 2 Seat Motors Circuit Shorted

- Code Popularity: 494 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC B3921?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • 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
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How to Fix the DTC B3921?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

B3921 01 Group 2 Seat Motors Circuit Shorted to Battery or Open
B3921 02 Group 2 Seat Motors Circuit Shorted to Ground

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3921 code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

Code B3921 Description

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. The Seat Memory Control Module connects all of the motor control circuits on each power rail to a common reference point whenever they are not in operation. The module monitors all seat motor control circuits for a shorted to ground or voltage before enabling any seat motor.
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.

OBDII Code B3921 - Group 2 Seat Motors Circuit Shorted - AutoCodes.com
B3921 Code - Group 2 Seat Motors Circuit Shorted

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