B24A0

Code

Generic B — Body

Blind Spot Monitor Sensor Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 9 EN: 15 RU: 9

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Read freeze frame and all stored DTCs from the BSM and gateway modules with a capable scan tool
Verify vehicle battery voltage and inspect fuses related to BSM/ADAS circuits
Visually inspect sensor(s), connector(s) and wiring for damage, corrosion, or water ingress
Check connector mating and retention; reseat connectors and inspect pins
Measure sensor supply voltage and ground continuity at the connector
Check CAN/LIN bus for proper idle voltages and presence of messages (scan tool or oscilloscope)

Sensor supply voltage: typically ~11–14.5 V with ignition on (verify vehicle-specific range)
Sensor ground: near 0 V; low resistance to chassis ground
CAN bus idle voltages: CANH ~2.5–3.5 V, CANL ~1.5–2.5 V (both ≈2.5 V typical on many systems)
CAN differential during activity: pulses of ~1–2 V differential
Bus termination: total ≈60 ohms between CANH and CANL (two 120Ω in parallel typical)
Message periodicity: sensor reports at defined interval (vehicle-specific; typically several Hz) — scan tool should show regular messages when functional

Connect OEM-level scan tool. Read and record all stored DTCs and freeze-frame data from BSM and network gateway modules.
Confirm battery voltage stable and inspect related fuses/relays. Repair any low-voltage conditions before further testing.
Visually inspect the suspect BSM sensor(s), harness, and connectors for damage, corrosion, water, or pin deformation. Reseal or replace as needed.
With ignition ON, back-probe the sensor connector: verify supply voltage and ground. If supply or ground is out of range, trace and repair wiring or fuse.
Check the communication lines with a scan tool or oscilloscope: verify CAN/LIN idle voltages, presence of regular sensor messages, and correct termination. Repair shorts/opens as found.
Wiggle-test wiring and connectors while monitoring communication for intermittent faults. Repair any wiring harness damage found (splice/replace as required).
If voltages and wiring are good but no messages, swap the suspect sensor with a known-good unit (if available) or substitute a socketed harness to confirm sensor failure before replacement.
Check other modules for related U-codes (network) and address them as necessary. Clear codes and perform a guided self-test or relearn/calibration if required by the manufacturer.
After repairs, clear DTCs and perform a road test and re-scan to confirm the fault does not return. If persistent, escalate to module bench testing or consider module replacement per manufacturer guidance.

Water intrusion or corrosion at sensor connector causing intermittent communication
Damaged wiring harness behind the bumper/pillar where sensors are mounted
Failed sensor electronics (internal fault)
Loss of reference ground at sensor or module
Vehicle network (CAN/LIN) disturbance from aftermarket device or previous repair