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Home / DTC / B28A1 — Side latch motor:short to BAT

B28A1 — Side latch motor:short to BAT

Detailed page for trouble code B28A1.

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22,491specific
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Code

B28A1

MITSUBISHI B — Body

Side latch motor:short to BAT

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

Causes

  • Shorted wiring to battery (pin contact, chafing, or pinched harness)
  • Failed/shorted latch motor (internal short in motor windings)
  • Corroded or damaged connector allowing battery voltage to feed the circuit
  • Aftermarket accessory or improper repair spliced into circuit
  • Shorted relay or stuck output in the body/control module (less common)

Symptoms

  • Side latch (door/slide-door) will not operate properly (may be stuck closed or open)
  • Blown fuse or repeated fuse failures for latch circuit
  • Uncommanded latch motor actuation or inability to move latch when commanded
  • Burning smell or heat at connector/harness in severe cases
  • DTC B28A1 stored and possibly related warnings on body control module

What to check

  • Visually inspect wiring and connectors at the affected side latch, door hinge, and body harness for damage, chafing, corrosion, or pinched areas
  • Check fuses and relays for the latch motor circuit
  • With key off, check for battery voltage at the motor connector (voltage present when it should be off indicates short)
  • Scan vehicle and read freeze-frame/live data; note whether code is active, and whether related codes are present
  • Disconnect the latch motor connector and see if the code clears or if current draw stops (use scanner to monitor)

Signal parameters

  • Resting voltage at motor connector with ignition off: ~0 V (no battery feed expected)
  • Voltage at connector when actuator commanded: ~12 V (or switched polarity depending on actuator type)
  • Motor coil resistance (one direction): typically low ohms — expected value depends on vehicle (measure and compare left/right or factory spec)
  • Cranking/activation current: motor should draw a few amps when running; excessive continuous high current indicates short or seized motor

Diagnostic algorithm

  1. Record code and any freeze-frame data with a scan tool. Note whether code is active or intermittent.
  2. Perform a visual inspection of the latch, motor, connector, and wiring along the path (hinge, door jamb). Look for abrasion, pinched insulation, or corrosion.
  3. Check fuses and related relays. Replace a blown fuse only after finding cause — do not repeatedly replace fuses without diagnosis.
  4. With ignition off, disconnect the latch motor connector. Clear the code, then attempt latch operation while monitoring the scan tool. If code does not return, the fault is in the motor or wiring downstream of the connector.
  5. Measure DC voltage at the disconnected motor connector with respect to ground when latch is not commanded and when commanded. Presence of battery voltage when not commanded indicates short to battery or stuck output.
  6. Measure motor coil resistance (with motor disconnected). Compare to spec or the opposite side if available. Very low resistance suggests internal short; open/very high suggests open circuit.
  7. If wiring short is suspected, use a backprobe or power-off continuity test to locate short. Repair damaged wiring, repair/replace connector terminals as needed.
  8. If motor is isolated as fault (internal short or seized), bench-test motor by applying appropriate fused 12V supply briefly to verify operation, then replace motor/assembly if faulty.
  9. After repairs, reconnect everything, clear codes, and perform function test for several cycles to confirm the code does not return.
  10. If wiring and motor check good and problem persists, consider module output driver fault and consult manufacturer procedures; avoid replacing control modules without thorough verification.

Likely causes

  • Wiring chafe/pinched at hinge or door jamb causing insulation wear and short to battery
  • Internal short in the latch motor assembly due to water/corrosion
  • Corroded/contaminated connector at the latch motor

Fault status

⚠️ Status
Side latch motor circuit — short to battery detected. High or unexpected battery voltage/current on latch motor circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B28A0 B28A2 B2801 B28B1 U0121
406

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