U041A

Code

Generic U — Network/User

Invalid Data Received From Battery Isolation/Voltage Stabilization Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 16 EN: 27 RU: 29

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

CAN/LIN communication errors between modules
Intermittent or open/shorted wiring/connectors to the BICM/VS
Power or ground fault at the BICM/VS
Faulty BICM/VS module (hardware or firmware)
Bus termination or wiring impedance issues
Software/version mismatch or corrupted calibration data

Symptoms

Battery isolation relay may not engage or disengage correctly
Reduced charging or unexpected battery drain behavior
Battery/charging warning lamp, MIL, or network warning lights
Vehicle may enter limp or reduced-power modes related to battery management
Intermittent functionality of features tied to battery isolation/stabilization

What to check

Read and record freeze frame and all related U and P codes with a capable scan tool
Check battery voltage and state of charge; verify battery terminals are clean and tight
Inspect BICM/VS connectors and wiring for corrosion, damage, or water intrusion
Verify module power and ground circuits at the BICM/VS with a DVOM
Scan for other modules reporting communication faults on the same bus
Use a scope or CAN bus analyzer to view CAN_H and CAN_L activity and message traffic

Signal parameters

CAN recessive single-ended voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V
CAN dominant single-ended voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
Typical CAN differential idle ≈ 0 V, dominant ≈ 2 V (values vary by vehicle)
Expected message IDs, message frequency and payload for BICM/VS (refer to OEM data)
Checksum/CRC and expected payload length for battery isolation messages (OEM-specific)

Diagnostic algorithm

Retrieve all DTCs and freeze-frame data. Note related U-codes and timeframes. Clear codes and attempt to reproduce.
Verify battery health and terminal connections. Charge battery to nominal voltage and retest.
Visually inspect the BICM/VS connector and wiring harness; repair any corrosion, pin damage, or chafing.
Measure module supply voltage and ground at the BICM/VS connector with key on and engine off. Repair any faults.
Check for CAN bus activity with a scan tool: verify BICM/VS transmit messages appear and that other modules can see them.
Use an oscilloscope to compare CAN_H and CAN_L waveforms to expected voltages and look for noise, missing recessive/dominant states, or bus collisions.
Measure termination resistance across CAN_H and CAN_L (vehicle off); value should be near 60 ohms. Investigate if open or out-of-spec.
If bus wiring and power/ground are good, confirm software levels: check for module calibration/software updates or reflash per OEM procedures.
If possible, swap the BICM/VS with a known-good unit or bench-test replacement to confirm module fault.
After repair or replacement, clear codes and perform a full system test to confirm normal communication and restore functionality.

Likely causes

Damaged or corroded connector pins at BICM/VS
Low battery or poor battery connections causing corrupted messages
Broken CAN_H or CAN_L wiring or poor splice
Missing/incorrect module software or failed module boot
Faulty CAN transceiver in BICM/VS or other module on same bus
Improper bus termination resistor value or open termination

Fault status

⚠️ Status

Invalid data received from Battery Isolation/Voltage Stabilization Control Module — communication or data integrity fault. Check wiring, power/ground, CAN bus signals, and module software.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours