U05BF

Code

Generic U — Network/User

Invalid Data Received From Trailer Backup Assist Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 30 EN: 54 RU: 28

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty Trailer Backup Assist control module (vehicle or trailer module)
Damaged or corroded trailer harness or connectors
Open/short to voltage or ground on CAN high/low wires
Poor power or ground to the trailer or vehicle module
Intermittent connection or water intrusion at connectors
Software mismatch or corrupted module programming

Symptoms

Trailer Backup Assist warning or fault displayed on dash
Trailer backup assist disabled or not engaging
Erratic or incorrect trailer guidance indications
Multiple communication or U‑codes present in the network
Intermittent loss of trailer detection when connected

What to check

Use a scan tool to read all U-codes and freeze frame data; record related codes on the CAN network
Visually inspect trailer connector (pins, corrosion, water intrusion) and vehicle-side harness
Verify fuses and relays for trailer and backup assist modules
Check module presence/ID on the network with a diagnostic tool
Measure battery voltage and module supply/ground voltages with key on/engine running as required
Monitor CAN High/Low communications with a scan tool or oscilloscope while operating trailer assist

Signal parameters

Trailer Backup Assist CAN message: expected periodic message (e.g., 50–10 Hz depending on manufacturer) with stable timing
Message length (DLC) expected by vehicle (commonly 8 bytes) — unexpected DLC may indicate corruption
Trailer presence/detection bit or flag (boolean) should match physical connection
Hitch/trailer angle values within plausible physical range (not all zeros or out-of-range spikes)
Checksum or CRC (if used) must validate — frequent checksum failures indicate corrupt data
CAN bus voltages: nominal CAN_H ≈ 2.5 V idle (dominant/recessive behavior present), differential voltage present during traffic

Diagnostic algorithm

Retrieve and document the U05BF code plus any other related U-codes and freeze frame data. Note conditions when the fault set (trailer connected, vehicle speed, ignition state).
Clear codes, perform a basic functional test (connect trailer, operate backup assist) to see if code returns and under what conditions.
Visually inspect trailer connector, seals and wires for corrosion, bent pins, water intrusion or damage. Repair any visible damage.
Verify battery voltage and supply/ground at the Trailer Backup Assist module and vehicle gateway module. Repair poor battery/ground connections.
Check fuses and relays for the trailer and assist system circuits; replace any failed components.
Using a diagnostic scan tool, verify the trailer module is present on the CAN network and monitor the expected messages (IDs, periodicity, DLC). Look for missing messages, malformed frames, or checksum failures.
With an oscilloscope or CAN bus analyzer, inspect CAN_H and CAN_L waveforms for noise, bus-off conditions, shorts to battery/ground, and correct differential signaling.
Perform a connector wiggle test and trailer harness flex while monitoring data; if the fault is intermittent, this may reveal a broken conductor or intermittent connection.
If aftermarket trailer electronics are installed, disconnect or disable them and re-test. Test with a known-good trailer or harness if available.
Check software/firmware levels for vehicle and trailer modules. Reprogram/reflash modules to latest calibration if manufacturer procedure recommends it.
If all wiring, power/ground and communications tests are good but invalid data persists, consider replacing the faulty Trailer Backup Assist control module per manufacturer diagnostic flow. After replacement, program/configure as required and verify system operation.
Clear codes and perform a full system function test including actual trailer backing maneuvers to confirm repair.

Likely causes

Corroded/blown trailer connector pins causing data corruption
CAN bus communication fault between trailer module and vehicle gateway
Trailer module firmware incompatible with vehicle software after an update
Loose ground or low supply voltage to the trailer/vehicle module
Trailer aftermarket device injecting invalid CAN messages

Fault status

⚠️ Status

Invalid or corrupted data received from Trailer Backup Assist control module (communication or data integrity failure). Trailer backup assist may be disabled.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 3.0 hours