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Home / DTC / B1B00 — Sub-module 'A'

B1B00 — Sub-module 'A'

Detailed page for trouble code B1B00.

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B1B00

LAND ROVER B — Body

Sub-module 'A'

Brand: LAND ROVER
Type: B — Body
Views: UK: 17 EN: 28 RU: 19
AI status
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Page language: EN

Causes

  • Loss of communication between the sub-module and vehicle networks (CAN/LIN)
  • No or intermittent power supply or poor ground to the sub-module
  • Damaged wiring harness or connector (corrosion, broken wires, bent pins)
  • Incorrect module coding or software mismatch after replacement or update
  • Internal sub-module hardware or software failure
  • Blown fuse or poor fuse connection supplying the module

Symptoms

  • Related body/electronic functions controlled by the sub-module may not operate or operate intermittently (locks, lights, windows, seats depending on module)
  • Warning or information messages illuminated on instrument cluster
  • Sub-module not present or is shown as 'no communication' in diagnostic tool
  • Stored multiple communication-related DTCs across modules
  • Vehicle security/immobilizer or central convenience features may be affected

What to check

  • Read and record freeze-frame and all related DTCs from all control modules with a capable scan tool
  • Check battery voltage and charging system; ensure battery >=12.4V (engine off) and charging when running
  • Inspect fuses and fusible links that supply the sub-module
  • Visually inspect the sub-module connector, wiring harness, and nearby harness routing for damage or corrosion
  • Check for other modules reporting comms errors (U-codes) to identify bus-wide problems
  • Verify module coding/software part number and software level against factory data

Signal parameters

  • Battery supply to module: ~12 V (engine off) to ~14.0–14.8 V (engine running)
  • Ground continuity:
  • CAN bus idle voltages: CAN H ≈ 2.5–3.5 V, CAN L ≈ 1.5–2.5 V; differential ~2.5 V when idle
  • CAN bus termination resistance: ~60 Ω (two 120 Ω terminators in parallel) between CAN H and CAN L
  • LIN bus idle voltage: ~12 V through pull-up or ~0–12 V depending on topology; check factory spec
  • Wake/sleep messages and node responses visible via factory-level scan tool (module should respond to CAN IDs/requests)

Diagnostic algorithm

  1. Connect a factory-capable scan tool and record B1B00 plus any related codes from all modules. Note freeze frame data.
  2. Attempt to clear the code and re-scan. If code returns immediately, proceed with communications and power checks.
  3. Verify battery state of charge and charging system. Recharge or replace battery if low and re-test.
  4. Inspect fuses and relay(s) feeding the sub-module; replace any blown fuses and verify power at the module connector with key on.
  5. Visually inspect the module connector and harness; unplug and check for bent pins, corrosion, or water intrusion. Clean/pin repair as required.
  6. Check ground connections for the module and adjacent ground straps for tightness and corrosion; measure continuity to battery negative.
  7. Use a scope or DMM to check CAN/LIN bus signals at the module connector for correct idle voltages and activity while operating/commanding functions.
  8. Measure CAN bus termination resistance between CAN H and CAN L. Repair wiring or termination faults if out of range.
  9. If wiring/power/ground and bus signals are normal, verify module software/coding level. Reflash or reprogram the module per factory procedure or apply available TSB update.
  10. If suspected module internal fault after the above, consult factory data regarding module swap procedures; perform a controlled replacement and code/program the new module. Retest all related functions and clear codes.
  11. If intermittent or complex network faults persist, capture bus logs while symptoms occur and escalate to manufacturer technical support if needed.

Likely causes

  • Connector corrosion or poor pin contact at the module
  • Broken or chafed CAN/LIN wiring near door hinges or moving parts
  • Module was replaced and not coded/programmed correctly
  • Battery drained or poor charging system causing intermittent resets
  • Ground strap or engine/rail ground degraded causing noise or intermittent operation

Fault status

⚠️ Status
B1B00 — Sub‑module 'A' fault. The vehicle detected a problem with the specified sub-module (communication, power/ground, configuration or internal fault). Further diagnosis required to identify whether the issue is wiring, power/ground, network communication, or the module itself.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-4 hours

Similar codes

B1B01 B1B02 U0100 U0140 U0073 U0401
160

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