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Home / DTC / B2642 — Body Control Module CAN Communication Fault

B2642 — Body Control Module CAN Communication Fault

Detailed page for trouble code B2642.

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Code

B2642

LAND ROVER B — Body

Body Control Module CAN Communication Fault

Brand: LAND ROVER
Type: B — Body
Views: UK: 8 EN: 12 RU: 7
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Page language: EN

Causes

  • Open, short or high resistance on CAN high/low wiring or connectors
  • Damaged or corroded BCM connector or pins
  • Failed BCM (internal transceiver or processor) or software fault
  • Faulty termination resistor(s) or incorrect bus topology
  • Low or erratic battery voltage / poor ground connections
  • Intermittent wiring damage (chafing, water intrusion) or recent bodywork modifications

Symptoms

  • No communication with BCM via diagnostic tool or intermittent connection
  • Multiple unrelated module warnings or lamp illumination (airbag, ABS, instrument cluster)
  • Central locking, lighting or convenience features inoperative or erratic
  • Keyless entry/remote start problems
  • Modules reporting other U or B communication codes
  • Engine may not crank if immobilizer or gateway communication is lost

What to check

  • Connect a diagnostic scan tool and confirm B2642 and any related U/B codes; record freeze-frame and timestamps
  • Check battery voltage (should be 12.4–12.8 V at rest, >11 V during cranking) and inspect main power/ground connections
  • Visually inspect BCM connector for corrosion, bent pins, water intrusion or heat damage
  • Check continuity and resistance of CAN H and CAN L between BCM and nearest modules; measure resistance across the bus (~60 Ω typical with two 120 Ω terminators in parallel)
  • Measure CAN voltages with key ON (no start): CANH ≈ 2.5 V (recessive) and CANL ≈ 2.5 V; dominant frames will show ~3.5 V (CANH) and ~1.5 V (CANL) — use oscilloscope for waveform verification
  • Perform wiggle test on wiring and connectors while monitoring bus for errors and drops

Signal parameters

  • Idle (recessive) voltage: CANH ≈ 2.5 V, CANL ≈ 2.5 V (each to chassis)
  • Dominant bit voltages (during traffic): CANH ≈ 3.5 V, CANL ≈ 1.5 V (approximate)
  • Bus resistance (two terminators): ≈ 60 Ω total (two × 120 Ω in parallel)
  • Typical CAN data rates used on body networks: 250 kb/s or 500 kb/s (verify manufacturer spec)
  • Transient noise, missing frames or bus-off conditions visible on oscilloscope when fault present

Diagnostic algorithm

  1. Read and record all stored/active DTCs and freeze-frame data with a capable scan tool. Note timing and related codes.
  2. Attempt communication with BCM. If no communication, confirm BCM has proper battery power and ground at the module connector.
  3. Visually inspect BCM connector and surrounding wiring for damage, corrosion, water ingress or repair splices; repair as necessary.
  4. Measure CANH and CANL voltages at the BCM connector with ignition ON. If voltages are out of expected range, isolate wiring and check for shorts to battery/ground.
  5. Check bus resistance between CANH and CANL with ignition OFF — expect ≈60 Ω. Remove modules/terminators as needed to isolate the short/open.
  6. Use an oscilloscope to view CAN waveforms while exercising functions or pressing buttons to create traffic. Look for missing frames, excessive noise, or dominant state stuck on the bus.
  7. Disconnect other modules or segments (one at a time) to isolate a faulty node causing bus errors. Re-check communication after each disconnect.
  8. If wiring and external modules check good, consider BCM internal failure. Verify latest software/calibration and reflash/update per manufacturer TSB before replacement.
  9. If BCM replacement is required, follow vehicle-specific programming, cloning or immobilizer pairing procedures. Clear codes and re-test the system for intermittent faults.
  10. Road test and re-scan to confirm fault does not return; investigate any intermittent or temperature-dependent failures further.

Likely causes

  • Faulty or corroded connector at the BCM
  • Broken or shorted CAN-H or CAN-L wiring near BCM
  • Failed BCM CAN transceiver
  • Improper bus termination (missing/failed 120 Ω resistors) or additional splices

Fault status

⚠️ Status
B2642 — BCM CAN Communication Fault: Body Control Module not communicating correctly on CAN network.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

U0073 U0100 U0121 U0140 U0155
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