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Home / DTC / B28A3 — Side latch motor:unexpect block

B28A3 — Side latch motor:unexpect block

Detailed page for trouble code B28A3.

34,405codes
59brands
11,914generic
22,491specific
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Code

B28A3

MITSUBISHI B — Body

Side latch motor:unexpect block

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Foreign object or debris blocking latch mechanism
  • Damaged or bent latch linkages or gears
  • Worn or seized latch motor or internal gear set
  • Failed motor windings or brushes causing intermittent stall
  • Poor electrical connection (corroded/loose connector, broken wire)
  • Insufficient supply voltage or intermittent ground

Symptoms

  • Side door will not latch, unlatch, open, or close automatically
  • Motor makes unusual grinding, clicking, or humming noises
  • Intermittent operation of side door functions
  • Warning chime or message related to door/lock
  • Related convenience or safety systems inhibited (e.g., inability to lock vehicle)

What to check

  • Read and record freeze frame / event data and all related DTCs with a compatible scan tool
  • Visually inspect the door/latch area for foreign objects, ice, rust, or deformation
  • Operate the door while observing latch and motor operation (use assistant) and listen for abnormal noises
  • Inspect motor connector for corrosion, bent pins, water ingress, or loose terminals
  • Check wiring harness for chafing, pinches or broken conductors between the motor and body control module
  • Measure supply voltage and ground at the motor connector during an operation attempt

Signal parameters

  • Command voltage at motor connector: approximately battery voltage (~12 V) when commanded ON
  • Ground continuity: close to 0 ohms to chassis ground
  • Motor stall current: higher than running current — compare to OEM spec; significant rise indicates mechanical bind or motor fault
  • Noisy or intermittent voltage signal during operation may indicate poor connection or intermittent driver output
  • Controller may report motor position feedback or run-time exceedance depending on model

Diagnostic algorithm

  1. Retrieve all DTCs and relevant data with a scan tool; note whether B28A3 is current or historic and if other door/lock codes are present.
  2. Attempt normal door operation while watching the latch and motor. Note noises, hesitation, or visible jamming.
  3. Perform a visual inspection of the latch, striker, door track and surrounding area. Remove any debris, ice, or foreign objects.
  4. With ignition ON, backprobe the motor connector while operating the latch: verify battery voltage on the power lead and a switched ground or driver signal on the control lead. Compare to expected behavior when commanded.
  5. Measure motor winding resistance with connector disconnected. A very low resistance (short) or open circuit indicates motor or wiring failure.
  6. Measure current draw during operation (use clamp meter). Excessive current indicates mechanical binding or internal motor fault; zero/low current with correct command indicates open wiring or poor connection.
  7. Inspect and wiggle the wiring harness and connector while monitoring voltage/current to check for intermittent faults.
  8. If electrical supply and control signals are good but motor stalls, remove the latch/motor assembly and inspect internal gears and linkages. Check for wear, damage, or debris. Manually operate latch to assess free movement.
  9. If motor is suspected faulty, bench-test motor with a regulated 12 V supply to confirm operation and current draw. Replace motor/actuator or latch assembly if required.
  10. Repair or replace damaged wiring, connectors, motor, or latch parts as indicated by findings. Reassemble, clear codes, and perform function tests and full system calibration if required by manufacturer procedures.
  11. After repair, perform several complete open/close cycles and re-scan for stored or pending codes to confirm resolution.

Likely causes

  • Mechanical obstruction in latch or door track
  • Seized or worn latch motor or gearbox
  • Loose/corroded connector or broken wire at motor
  • High current draw due to internal motor failure leading to stall

Fault status

⚠️ Status
Controller detected unexpected block or stall in side latch motor; motor movement interrupted or excessive resistance detected during commanded operation.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B28A1 B28A2 B28A4 B28B0 B2800
406

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