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Home / DTC / U041A — Invalid Data Received From Battery Isolation/Voltage Stabilization Control Module

U041A — Invalid Data Received From Battery Isolation/Voltage Stabilization Control Module

Detailed page for trouble code U041A.

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U041A

Generic U — Network/User

Invalid Data Received From Battery Isolation/Voltage Stabilization Control Module

Brand: Generic
Type: U — Network/User
Views: UK: 11 EN: 18 RU: 17
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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

  1. Retrieve all DTCs and freeze-frame data. Note related U-codes and timeframes. Clear codes and attempt to reproduce.
  2. Verify battery health and terminal connections. Charge battery to nominal voltage and retest.
  3. Visually inspect the BICM/VS connector and wiring harness; repair any corrosion, pin damage, or chafing.
  4. Measure module supply voltage and ground at the BICM/VS connector with key on and engine off. Repair any faults.
  5. Check for CAN bus activity with a scan tool: verify BICM/VS transmit messages appear and that other modules can see them.
  6. 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.
  7. Measure termination resistance across CAN_H and CAN_L (vehicle off); value should be near 60 ohms. Investigate if open or out-of-spec.
  8. If bus wiring and power/ground are good, confirm software levels: check for module calibration/software updates or reflash per OEM procedures.
  9. If possible, swap the BICM/VS with a known-good unit or bench-test replacement to confirm module fault.
  10. 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

Similar codes

U0100 U0401 U0415 U0141 U0420
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