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Home / DTC / B1D39 — Rear right door module CAN bus communication fault

B1D39 — Rear right door module CAN bus communication fault

Detailed page for trouble code B1D39.

35,017codes
59brands
11,925generic
23,092specific
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Code

B1D39

LAND ROVER B — Body

Rear right door module CAN bus communication fault

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

Causes

  • Open or short in CAN High or CAN Low wiring to the rear right door module
  • Poor or corroded connector pins at the door module or body harness (water ingress, corrosion, bent pins)
  • Failed rear right door module (internal CAN transceiver or electronics)
  • Failed gateway/junction box or intermediate module on the vehicle CAN network
  • Missing or incorrect CAN termination (open or shorted termination resistors)
  • Intermittent battery, ground, or supply voltage to the door module

Symptoms

  • DTC B1D39 stored in vehicle network
  • Rear right door features inoperative or intermittent (power window, central locking, mirror, courtesy light)
  • Possible inability to lock/unlock that door with RKE or central locking
  • Warning messages or control modules reporting 'no communication' for door module
  • Other modules showing network errors or reduced functionality if bus is stressed

What to check

  • Read all stored codes from all modules and note freeze frame / occurrence data
  • Confirm symptom and whether DTC is permanent, intermittent, or current
  • Visual inspection of rear right door harness, connector, and module for corrosion, damage, water ingress
  • Check module supply and ground voltages at the rear right door module connector with ignition on
  • Measure CAN_H and CAN_L voltages at the module connector (idle and during communication)
  • Measure resistance across CAN_H and CAN_L at two ends to verify approx. 60 Ω termination

Signal parameters

  • Idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each relative to chassis ground) — differential ≈ 0 V
  • Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V — differential ≈ 2 V
  • Bus termination: approximately 60 Ω measured between CAN_H and CAN_L (two 120 Ω in parallel)
  • Typical high-speed CAN data rates used on doors: 500 kb/s or 250 kb/s depending on model — verify OEM specification
  • Look for excessive noise, missing frames, or bus-off conditions when capturing with a scope or CAN analyzer

Diagnostic algorithm

  1. Retrieve freeze frame and full DTC list. Note if other network U- or B-codes are present (can help locate network failure).
  2. Recreate symptom if safe. Note if fault is permanent or intermittent and whether it correlates with door movement.
  3. Visually inspect the rear right door module connector and harness at the door and sill for corrosion, broken wires, or pin damage. Repair any visible damage.
  4. With ignition on, measure module supply voltage and ground continuity. Repair any supply/ground issues before further tests.
  5. Backprobe the CAN_H and CAN_L at the door module connector. With engine/ignition on, verify idle voltages and look for normal differential during communication using a scan tool or oscilloscope.
  6. Check termination resistance between CAN_H and CAN_L at two remote points (e.g., module connector and gateway) — expect ~60 Ω total. If open or very low, isolate and repair short/open.
  7. Perform a wiggle test of the door harness (hinge area) while monitoring the bus for noise or loss of frames to identify intermittent breaks.
  8. Inspect/repair any damaged wiring. If wiring and connectors check good but communication is absent only for that module, consider replacing or bench-testing the door module.
  9. If a replacement module is installed, ensure correct VIN programming or module coding and perform any required reinitialization or software updates per OEM procedures.
  10. Clear codes and verify repair by cycling ignition and exercising door functions. Monitor for reoccurrence while driving and during door operation.

Likely causes

  • Corroded/loose connector at rear right door module (common due to door motion and moisture)
  • Broken or chafed CAN wiring in door harness near the hinge
  • Faulty door module CAN transceiver
  • Incorrect or failed CAN termination resistor (low or open resistance)
  • Intermittent module supply/ground causing the module to drop off the bus

Fault status

⚠️ Status
No or intermittent CAN communication with the rear right door module — module not responding on the vehicle CAN network.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 3.0 hours

Similar codes

B1D38 B1D3A U0073 U0100 U0155 B1D40
413

Browse 413 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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