B1B72

Code

LAND ROVER B — Body

Local interconnection network bus 1 - power source circuit nutrition

Brand: LAND ROVER

Type: B — Body

Views: UK: 10 EN: 28 RU: 16

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Page language: EN

Causes

Blown fuse or fusible link supplying LIN Bus 1
Open or high-resistance power feed (battery/ignition feed) to the LIN transceiver
Damaged wiring harness or connector (corrosion, chafing, broken conductor)
Poor or missing ground at related module(s)
Short to ground or short to battery on the LIN supply circuit
Faulty LIN transceiver or control module (body module, BCM, gateway)

Symptoms

Loss of communication with devices on LIN Bus 1 (e.g., climate, seat, doors, steering wheel controls)
Multiple unrelated modules reporting faults or going into limp mode
Intermittent operation of LIN-controlled functions
Warning lights or messages on instrument cluster about communication faults
Reduced vehicle functionality related to body systems

What to check

Connect a diagnostic scan tool and read all network and module communication errors; note freeze-frame data
Check battery voltage (engine off and running) and charging system health
Inspect and test relevant fuses and fusible links for continuity
Visually inspect wiring harnesses and connectors for damage, corrosion, water ingress, and secure mating
Check module power and ground pins for proper voltage and good ground
Backprobe the LIN supply and transceiver power pin with a multimeter or scope while cycling ignition and operating affected functions

Signal parameters

LIN bus supply (Vbat feed) typically equals battery voltage when ignition on: approx. 11–15 V
LIN bus idle state (single-wire) is nominally pulled to battery voltage; dominant state is pulled low toward 0 V during messages
Dominant low pulses are near 0 V; recessive (idle) near Vbat
With ignition off some LIN circuits may not be powered — check expected presence per wiring diagram
Measured resistance from supply to ground (ignition off) should be high; a low resistance suggests a short

Diagnostic algorithm

Use a scan tool to read/all communications faults and clear codes; attempt to reproduce the fault and note when it returns.
Verify battery voltage and charging system; charge or replace battery if low.
Locate and inspect the fuse/fusible link that supplies LIN Bus 1; verify continuity and correct amperage.
With ignition ON, measure voltage at the LIN supply pin on the gateway/BCM and at downstream modules; compare to battery.
Check module ground(s) for low resistance to chassis ground; clean/tighten as needed.
Visually inspect wiring harnesses along known vulnerable areas (doors, sills, steering column) for damage; repair any faults.
If supply voltage is missing or intermittent, disconnect downstream modules one at a time to isolate a shorting/overloading module.
Use an oscilloscope to observe LIN waveform for proper recessive/dominant behavior and for noise or interruptions.
If wiring and connectors are good and a single module shows abnormal behavior, replace or reprogram that module per manufacturer guidance.
After repairs, clear codes and verify proper operation of LIN-controlled systems and that B1B72 does not return.

Likely causes

Blown inline fuse that powers LIN Bus 1
Connector corrosion at gateway or body control module power pin
Open battery feed due to damaged harness in door sill/hinge area
Faulty module pulling the LIN supply to ground
Weak battery causing LIN supply to drop under load

Fault status

⚠️ Status

LIN Bus 1 power supply circuit fault — supply voltage missing or intermittent causing loss of LIN network nutrition.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.5 hours

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B1B72 — Local interconnection network bus 1 - power source circuit nutrition