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B1A6A — Failure in the left mirror control module

Detailed page for trouble code B1A6A.

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Code

B1A6A

LAND ROVER B — Body

Failure in the left mirror control module

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

Causes

  • Open or shorted wiring to the left mirror control module
  • Corroded or loose connector at mirror or body harness
  • Blown fuse or interrupted power/ground
  • Internal failure of the mirror control module
  • Loss of CAN/LIN communication between module and body control module (BCM)
  • Water ingress or physical damage to the mirror assembly

Symptoms

  • Left side mirror fails to adjust with door switch
  • Mirror folding/unfolding doesn't operate or is intermittent
  • Heated mirror element does not warm or is inconsistent
  • Warning or DTC indicator on dash relating to exterior mirror
  • Audible clicking or motor noise but no movement, or no activity at all
  • Other body modules report communications errors or multiple related DTCs

What to check

  • Read all stored and pending codes with a factory-level scan tool; note freeze frame and module responses
  • Visually inspect the left mirror, wiring loom and connector for damage, corrosion or water ingress
  • Check related fuses and relays for continuity and correct rating
  • Wiggle test the door harness while observing live data and fault appearance
  • Measure supply voltage (approx. battery voltage) and ground at the mirror connector with ignition on
  • Check CAN/LIN bus continuity and voltages (idle ~2.5 V for CAN) and message presence with a suitable scan tool

Signal parameters

  • Supply voltage at mirror control module pin — should be battery voltage with ignition on
  • Ground continuity — low ohms to chassis ground
  • CAN High / CAN Low voltages — idle ~2.5 V (verify with manufacturer spec)
  • Resistance of heated mirror element (ohms) — compare to specification
  • Motor actuation current draw (amps) during adjust/fold — excessive or open indicates motor/gear fault
  • PWM frequency or duty cycle for mirror motor control (where applicable)

Diagnostic algorithm

  1. Retrieve B1A6A and any related codes; record module addressing and faults from the scan tool.
  2. Clear codes and attempt to reproduce the fault to confirm it's current. If intermittent, perform wiggle test on harness while monitoring live data.
  3. Visually inspect mirror housing and connector for corrosion, water, damage. Repair/clean as needed.
  4. Verify fuses and relays powering the mirror circuit; replace if faulty.
  5. With ignition on, measure supply voltage and ground at the mirror connector. Confirm expected voltages per vehicle spec.
  6. Check continuity of wiring between mirror connector and body harness/BCM. Repair any opens or high resistance.
  7. Using a scan tool, monitor CAN/LIN messages and module responses. If no communication, trace bus for opens/shorts and check related modules.
  8. If power/communications are present, command mirror functions via diagnostic tool and measure motor current and heater resistance. Compare to spec.
  9. If mirror module is non-responsive but power and bus are good, consider reflashing/config update per manufacturer, then repeat tests.
  10. If module remains faulty after configuration attempt, replace the left mirror control module or entire mirror assembly as per service procedure. Program/configure new module and verify operation.
  11. After repairs, clear codes and perform a full function test of mirror adjust, fold, heating and any integrated features. Confirm no return of B1A6A.

Likely causes

  • Corroded/loose connector at the door mirror or splice
  • Water intrusion causing intermittent contacts or short circuits
  • Failed mirror control module
  • Blown fuse or missing supply/ground to the mirror
  • CAN bus communication fault (open, short, or high resistance)

Fault status

⚠️ Status
Left mirror control module fault detected. The module is reporting a malfunction or loss of expected signals (power, ground or bus communication). Functions such as mirror adjust, folding or heating may be affected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

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