B2B44

Code

Generic B — Body

Body Control Module — Keyless Entry Antenna Circuit Fault

Brand: Generic

Type: B — Body

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AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in antenna supply or signal wiring
Corroded, loose, or damaged antenna connector
Water intrusion or physical damage to antenna module
Failed keyless entry antenna module
Poor ground at antenna or BCM
Blown fuse or faulty power supply to antenna

Symptoms

Keyless remote/wireless lock/unlock does not work or has reduced range
Intermittent operation of remote locking/unlocking or passive entry
Doors fail to lock/unlock from remote while mechanical key works
Vehicle alarm or immobilizer may not arm/disarm reliably
Related DTC stored in BCM and possible warning/message on dash

What to check

Read and record DTC(s) and freeze frame data with a scan tool
Verify vehicle and key fob batteries have adequate charge
Perform a visual inspection of antenna location, connector, and wiring for damage or corrosion
Check fuses and power supply circuits for the antenna/BCM
Measure supply voltage and ground at the antenna connector with key fob button pressed
Check continuity between antenna module and BCM connector pins

Signal parameters

Antenna supply voltage: verify presence of specified supply (commonly 5 V or 12 V depending on vehicle) — consult service manual
Ground: continuity to body ground; resistance should be very low (
Signal: RF bursts present on antenna when fob button pressed (RF carrier frequency depends on market — typically ~315 MHz, 433 MHz, or 868 MHz); confirmed with RF/spectrum tool
BCM input: digital/analog input should show activity on scan tool or oscilloscope when remote is operated
Harness continuity: near-zero ohms for power/ground; low, stable resistance for signal conductor(s)

Diagnostic algorithm

Connect a scan tool, retrieve codes and freeze frame. Note any related body or immobilizer codes.
Verify vehicle battery voltage is within specification. Replace weak vehicle battery if necessary. Verify key fob battery is good.
Visually inspect the antenna, its mounting location, and connectors for water intrusion, corrosion, or physical damage.
Check relevant fuses and relays for the BCM/antenna circuits; replace if blown.
With connector disconnected, check for proper supply voltage and ground at the antenna connector. Repair supply/ground faults before proceeding.
Measure continuity between the antenna connector and the BCM pins. Repair any open or high-resistance circuits and secure connectors.
With the fob operated, verify a signal/activity at the antenna output using appropriate RF test equipment or an oscilloscope hooked to the signal line (if applicable).
Perform a wiggle test of the harness and antenna while monitoring for faults or changes in live data. Pay attention to intermittent faults caused by corrosion or broken wires.
If wiring and power/ground are good but no proper signal is present, replace or bench-test the keyless entry antenna module with a known-good unit.
If a replacement antenna does not clear the code and wiring checks good, consider BCM input circuit failure. Reprogram or replace the BCM only after confirming wiring and antenna are good.
After repairs, clear codes and retest remote functions and drive/operation to confirm the fault does not return.

Likely causes

Damaged/loose antenna connector or corroded pins
Open or short in antenna harness between antenna and BCM
Antenna module failure (water-damaged or internal component fault)
Blown fuse or missing supply/ground to antenna
Intermittent BCM input — rare but possible if wiring and antenna check OK

Fault status

⚠️ Status

BCM detected a fault on the keyless entry antenna circuit (open/short/intermittent or antenna/module failure). Storage of B2B44 indicates the BCM is not receiving expected antenna input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours