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Home / DTC / B1A86 — Ignition status

B1A86 — Ignition status

Detailed page for trouble code B1A86.

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Code

B1A86

LAND ROVER B — Body

Ignition status

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

Causes

  • Faulty ignition switch or keyless start push-button
  • Damaged or corroded wiring/connectors between ignition switch and body control module (BCM)
  • Blown fuse or faulty ignition/start relay
  • Weak or discharged battery or poor battery terminal connection
  • Faulty body control module, steering column module, or ignition module
  • CAN bus or network communication errors between modules

Symptoms

  • Engine will not crank or intermittent no-start condition
  • Accessories do not power in Accessory/Run positions or behave inconsistently
  • Dash instrumentation does not change with key positions or shows incorrect status
  • Starter engages only intermittently or only when jiggling key/wiring
  • Multiple communications or body-related DTCs present (CAN or module loss)
  • Vehicle may enter limp/security mode or starter disabled

What to check

  • Read all stored codes and freeze frame data with a manufacturer-capable scan tool; note any related U-codes or security codes
  • Verify battery voltage (static and cranking) and check battery terminals for corrosion/tension
  • Inspect fuses and relays related to ignition and BCM; test/replace if suspect
  • Visually inspect wiring and connectors at ignition switch, steering column module, and BCM for damage, corrosion, or loose pins
  • Using DVOM or oscilloscope, verify ignition position signal voltages at the ignition switch connector for Off/ACC/Run/Start positions
  • Check continuity and resistance between ignition switch output and BCM input pins; look for shorts to ground or Vbat

Signal parameters

  • Keyless/ignition switch output voltage: ~0 V (Off), ~10–12 V (Accessory/Run depending on design), near battery voltage when Run/Start — verify with vehicle reference values
  • Start cranking signal: switched to starter relay/solenoid during 'Start' position — continuity and voltage present only in Start
  • Typical circuit continuity: near 0 ohms between switch terminal and BCM input under normal wiring (exact ohm depends on harness length)
  • CAN bus voltage nominal ~2.5 V differential idle, proper CAN traffic should be present on both CAN_H and CAN_L lines
  • Watch for pulse/async patterns on keyless start push-button modules — refer to manufacturer waveform specifications

Diagnostic algorithm

  1. Connect scan tool, record B1A86 and any related codes, capture freeze frame and live data while cycling ignition positions.
  2. Verify battery condition and charge; ensure battery voltage is >12.4 V and cranking voltage >9.6 V. Clean/retighten battery terminals.
  3. Inspect and test fuses and relays for ignition circuits; replace suspect items.
  4. Cycle key to each position and observe scan tool live data for ignition status bits/flags; note if BCM receives correct position changes.
  5. With ignition cycled, measure ignition switch output voltages at the switch connector for Off/ACC/Run/Start. Compare to expected values. If outputs are wrong, suspect switch or wiring.
  6. If switch outputs are correct, trace and test wiring/continuity from switch to BCM/steering column module; repair any opens/shorts/corrosion.
  7. Check CAN bus integrity and module communications (U-codes); repair wiring or module causing communication loss.
  8. Verify immobilizer/key recognition; try a known-good key or reprogram key per manufacturer procedure if immobilizer faults present.
  9. If wiring and keys check OK, consider BCM or steering column module fault; confirm with module bench test or swap with known-good unit per workshop procedures and after verifying programming requirements.
  10. After repairs, clear codes and retest multiple ignition cycles, verify no reoccurrence and proper starting/accessory behavior.

Likely causes

  • Failed ignition switch contacts or internal sensor
  • Open/short in ignition-run/start circuit wiring harness
  • Poor ground or battery supply to BCM or ignition circuit
  • Intermittent connector pin or corrosion at BCM or steering column connector
  • Immobilizer not recognising key (antitheft preventing ignition status update)

Fault status

⚠️ Status
Ignition status fault reported by body/control module: ignition position signal is missing, inconsistent, or not being received. May prevent correct accessory and start behavior or engage security/limp mode.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 3.0 hours

Similar codes

B1A85 B1A87 U0121 U0100 P0615
320

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