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Home / DTC / B1A82 — External Trigger Switch Circuit

B1A82 — External Trigger Switch Circuit

Detailed page for trouble code B1A82.

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

B1A82

LAND ROVER B — Body

External Trigger Switch Circuit

Brand: LAND ROVER
Type: B — Body
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Page language: EN

Causes

  • Open or shorted wiring between the external trigger switch and the control module
  • Faulty or worn external trigger switch (mechanical/electrical failure)
  • Poor connector connection, corrosion, bent pins or water ingress at the switch or module connector
  • Blown fuse or poor fused power/ground to the circuit
  • Faulty body/control module input or internal damage
  • Software/configuration issue or intermittent fault not persistent

Symptoms

  • Associated accessory or function controlled by the external trigger does not activate
  • Intermittent operation of the external function (works sometimes)
  • Warning or message on dash related to the affected function
  • DTC stored and possibly lamp illuminated
  • No response when the external trigger is operated

What to check

  • Retrieve all stored DTCs and freeze-frame data with a diagnostic scanner; note conditions when fault set
  • Visually inspect switch, mounting area and wiring harness for damage, corrosion, water ingress or loose pins
  • Check related fuses and power/ground at the switch connector
  • Backprobe the switch connector while operating the switch and confirm signal changes to the control module
  • Measure resistance/continuity of switch wiring between switch and module, checking for opens or shorts to ground/battery
  • Check for any service bulletins or software updates related to body module inputs

Signal parameters

  • Typical reference voltage: 5 V or 12 V feed to switch (varies by application) — verify against manufacturer data
  • Inactive signal: ~0 V (ground) or open circuit depending on switch type
  • Active signal: close to battery voltage (~12 V) or pulled to ground depending on circuit design
  • Expected continuity across switch contacts when activated: low ohms (near 0 Ω)
  • Expected open circuit when switch released: high resistance/OL

Diagnostic algorithm

  1. Confirm the fault: read B1A82 and related codes, record freeze-frame and symptom details.
  2. Reproduce the symptom and observe operation while monitoring the scanner live data for the external trigger input.
  3. Perform a visual inspection of the switch, connector and wiring for damage, corrosion or moisture. Repair any obvious issues.
  4. With ignition on, backprobe the switch connector and operate the switch. Verify reference power, ground and the signal change at the connector.
  5. If no signal change at the switch but module sees a change (or vice versa), isolate by measuring at wiring harness and at the module connector to locate open/short.
  6. Check continuity between switch and module pins. Wiggle test harness while monitoring continuity to find intermittent breaks.
  7. If wiring and connector are good, bench-test or temporarily substitute a known-good switch (or jumper the switch circuit appropriately) to confirm switch vs harness/module.
  8. If switching correctly at the switch but module input does not respond, inspect module connector for corrosion and test module ground and power. Consider module replacement only after isolating wiring and switch faults.
  9. Clear codes and retest to ensure fault does not return. If intermittent, monitor over several ignition cycles and operating conditions.
  10. If required, consult manufacturer technical service information for wiring diagrams, connector pinouts and software updates before replacing modules.

Likely causes

  • Connector corrosion or water damage at the switch
  • Broken wire or chafed insulation causing intermittent short to ground or power
  • Failed switch contacts (stuck, welded, high resistance)
  • Loose ground at chassis/body control module
  • Failed input driver in the body control module

Fault status

⚠️ Status
External Trigger Switch Circuit fault — signal out of range (open/short/intermittent) detected by body/control module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

B1A80 B1A81 B1A83 B1A84 U0140
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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