Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / B1A87 — Battery disconnect / electronic control unit reset

B1A87 — Battery disconnect / electronic control unit reset

Detailed page for trouble code B1A87.

34,357codes
59brands
11,866generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

B1A87

LAND ROVER B — Body

Battery disconnect / electronic control unit reset

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

Causes

  • Battery disconnected intentionally (service) or accidentally
  • Dead or severely discharged battery
  • Loose, corroded or damaged battery terminals / cable
  • Intermittent main power supply or ground connection
  • Battery monitoring sensor or BCM fault
  • Blown main fuse or fusible link

Symptoms

  • Warning lights illuminated (multiple modules) after restart
  • Radio presets, clock and seat/memory settings reset to defaults
  • Possible no-crank or difficult starting
  • Loss of learned adaptations (idle, transmission shift points)
  • Temporary loss of communication with one or more modules
  • Stored related DTCs for low voltage or lost communication

What to check

  • Read and record all stored and pending codes and freeze-frame data from all modules
  • Inspect battery terminals and cable condition for corrosion, tightness and damage
  • Measure battery voltage (resting, key-on, cranking) and check state of charge
  • Verify main power and ground connections at battery and body/chassis grounds
  • Inspect main fuses/fusible links and fusible links in battery feed circuits
  • Check for recent service history (battery replacement, ECU programming) and verify procedure completion

Signal parameters

  • Battery voltage (V) — key off, key on, cranking
  • Module supply voltage and ground continuity
  • CAN bus activity and module communication status
  • Battery current / state-of-charge from battery sensor (if equipped)
  • Ignition / accessory power feed signals
  • Event timestamps in BCM/module log (time of disconnect/reset)

Diagnostic algorithm

  1. Connect a professional scan tool and record all current/pending DTCs and freeze-frame data from all modules.
  2. Note the time/date stamp or occurrence counter for B1A87 and check related module logs to correlate with owner history or service events.
  3. Visually inspect battery, terminals and cables; clean and tighten terminals as needed. Check for damaged wiring at battery posts.
  4. Measure battery resting voltage and state of charge. Perform battery load or conductance test to confirm battery health.
  5. With a DVOM or scope, check battery voltage during key-on and cranking; observe for drops below expected thresholds (for example
  6. Check main fuse/fusible link integrity and power distribution to body control and ECU modules.
  7. Inspect and test ground connections (battery negative to chassis/engine) for resistance and secure attachment.
  8. If battery and connections are good, scan BCM/battery monitor for sensor faults and verify software levels; look for interrupted programming events.
  9. If parasitic drain suspected, perform parasitic current test to identify aftermarket or internal drain sources.
  10. If an ECU or BCM fault is suspected, consult Land Rover technical service information for diagnostic procedures, update module software if available, then clear codes and road test to monitor for reoccurrence.
  11. Repair or replace failed components (battery, cables, sensor, module or wiring) as indicated by test results, then erase codes and confirm no return of the B1A87 code.

Likely causes

  • Poor battery connection (loose clamp, corrosion)
  • Weak/failed battery or low state of charge
  • Faulty battery current/voltage sensor or Battery Monitoring Module
  • Intermittent wiring fault on battery positive or ground circuits
  • Interrupted programming event or failed ECU flash
  • Blown main fuse supplying control modules

Fault status

⚠️ Status
Stored when the vehicle detects an interruption to the battery supply or an ECU reset event. Indicates a loss of power to one or more control modules or an unexpected module reset; further diagnostics required to identify the root cause.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1A86 B1A88 P0562 P0563 U0100 U0121
320

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

LAND ROVER

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .