B3469

Code

Generic B — Body

Keyless Entry Module Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 0 EN: 7 RU: 0

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open/short in communication bus wiring (CAN or LIN) between keyless entry module and body/gateway module
Poor or corroded connector or pin at the keyless entry module
Loss of power or ground to the keyless entry module (fuse, wiring, connector)
Module software mismatch or configuration error after replacement or update
Module internal failure (electronic fault)
Bus termination fault or excessive bus load/noise

Symptoms

Keyless entry functions intermittent or non-functional (lock/unlock, remote start, trunk release)
No response from remote fob or inconsistent behavior
Related modules show communication or network faults (other U- or B-codes)
Security/immobilizer light may be on or vehicle may not accept key
Possible inability to program or recognize key fobs

What to check

Scan for stored/complementary DTCs (U- and B-codes) and read freeze-frame data
Verify battery voltage at vehicle (~12V) and at module power terminal
Inspect fuses and fusible links for keyless entry and vehicle body modules
Visually inspect connectors and harness near the keyless module for corrosion, water ingress, or pin damage
Check for CAN/LIN bus activity with a scan tool or scope at the module connector
Measure resistance between CAN high/low or LIN and ground to find shorts

Signal parameters

CAN_H and CAN_L idle voltages ~2.5 V each; differential near 0 V (recessive) and ~2 V differential when dominant
LIN line idle voltage ~battery through pull-up (≈12 V or vehicle-specific pull-up to ~5 V on some systems)
Module supply voltage (B+) nominal 11.5–14.5 V while engine running
Ground resistance: low (near 0 Ω) between module ground and chassis
Message IDs and frequency for keyless entry frames as expected (use manufacturer list or gateway monitor)
Bus error counters or node-offline indicators shown by diagnostic tool

Diagnostic algorithm

Connect a capable scan tool and record DTCs, freeze-frame, and live data. Note any related U-codes or repeated communications errors.
Verify vehicle battery state and inspect/replace blown fuses related to body/keyless modules.
Visually inspect keyless module connector and harness for corrosion, bent pins, water damage or physical faults. Repair as needed.
With ignition on, check module power and ground pins for proper voltage and continuity to chassis ground.
Using scanner or oscilloscope, monitor CAN/LIN bus at the module connector: confirm message traffic, correct voltages, and absence of excessive noise or stuck dominant state.
If bus messages are missing only from the keyless module, probe wiring continuity between module and gateway/BCM. Repair open/shorts or bad splices.
If bus is off or showing multiple node errors, isolate by disconnecting suspected faulty modules or aftermarket devices, then re-test to find the failing node.
If wiring, connectors, fuses and bus termination are good but module does not communicate, check for required software updates or module reprogramming. Reflash or replace module if supplier procedure indicates.
After any repair, clear codes, perform full network scan and validate proper operation of keyless functions and that the DTC does not return.

Likely causes

Loose, corroded, or damaged connector at the keyless entry module
Blown fuse or missing 12V supply to the module
Open or shorted CAN/LIN wire near module or splice
Bus arbitration errors caused by missing termination or a short to battery/ground
Failed keyless entry module (less frequent than wiring/connector issues)

Fault status

⚠️ Status

Keyless Entry Module Communication Fault — the keyless entry module has detected loss or corruption of communication on the vehicle data bus or internally detected communication errors. Check power, ground, connectors, bus wiring and for module faults.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hrs