U0112

Code

HYUNDAI U — Network/User

Lost Communication With Battery Energy Control Module “B”

Brand: HYUNDAI

Type: U — Network/User

Views: UK: 10 EN: 23 RU: 22

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Page language: EN

Causes

Battery Energy Control Module B (BECE-B) failure
Faulty CAN bus wiring (open/short to ground or battery) between module and CAN network
Poor or corroded connector pins at module, junctions or gateway module
Blown fuse or loss of module power/ground (12 V supply or ground)
CAN bus arbitration / termination fault (missing 60 Ω termination or short)
Other module on same bus causing bus-off condition

Symptoms

MIL / warning lamp for EV/HEV system, battery charging, or multiple modules
Inability to charge or discharge HV battery properly; reduced vehicle performance or limp mode
Loss of hybrid/EV drive modes or no start condition for electric drive
Multiple communication-related DTCs present on scan tool
Instrument cluster may show communication warnings or missing data (SOC, HV status)
Possible reduced regenerative braking or charging disabled

What to check

Read and record all U-codes and freeze frame / data with a capable scan tool.
Verify 12V battery voltage and state (engine off and cranking).
Inspect fuses and relays supplying BECE-B and related gateway / CAN power circuits.
Visually inspect connectors at BECE-B, gateway, and CAN junctions for corrosion, bent pins, water intrusion, or looseness.
Check for presence of other related U-codes (bus-off, lost comm with gateway, module A) to identify scope.
Measure CAN bus voltages at a known good location and at BECE-B connector (see signal_params).

Signal parameters

Idle CAN bus (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V
Dominant CAN state: CAN_H ≈ 3.5–4.0 V, CAN_L ≈ 1.0–1.5 V (approximate values; confirm with manufacturer specs)
Termination resistance across CAN_H and CAN_L: ≈ 60 ohms (two 120 Ω terminators in parallel)
Module supply voltage (VBATT/IGN): approx. 11–14 V when system powered; check exact pin voltage per wiring diagram
Module ground: near 0 V with good connection
CAN data activity: bus traffic present when vehicle ignition ON; absence indicates missing module transmissions

Diagnostic algorithm

Connect a qualified scan tool and read all DTCs. Record freeze-frame and any dependent codes.
Verify vehicle battery and 12V system health. Recharge or replace battery if below specification.
Inspect BECE-B power and ground fuses/relays. Verify proper voltages at the BECE-B power connector with ignition ON and during attempted communication.
Visually inspect BECE-B harness and connectors for damage, corrosion, loose pins, or water. Repair as needed.
With ignition ON, use a DMM/oscilloscope to check CAN_H and CAN_L voltages at BECE-B connector and at the gateway/module junction. Compare to expected signal_params.
Check termination resistance across CAN_H and CAN_L at key points. If open or out of spec, locate and repair broken/removed terminator or short.
Perform continuity and short-to-power/ground checks on CAN wiring between BECE-B and gateway/TCU/BCM. Repair any shorts or opens.
If the bus is ‘bus-off’ due to another module, isolate sections of the network (disconnect suspected modules one at a time) and re-check communications to identify the offending module.
If power/ground and wiring check OK but no communication, attempt to communicate directly with BECE-B using the scan tool. If no response, suspect module failure.
Before replacing any module, verify with wiring diagrams and consider swapping with known-good module only when appropriate. Follow manufacturer procedures for module replacement and initialization.
After repairs, clear codes and perform a road test or system functional test to ensure normal communication and that the DTC does not return.
Safety note: HV system components may be present. Follow manufacturer high-voltage isolation and service procedures before accessing HV connectors or modules.

Likely causes

Blown fuse or disconnected 12 V feed / ground to Battery Energy Control Module B
Damaged or loose connector at the BECE-B module or at a CAN junction
CAN bus short to battery or ground between the module and gateway
Module hardware failure (BECE-B internal) after other checks
Gateway or BCM not forwarding CAN messages (fault in gateway/ECU)

Fault status

⚠️ Status

Lost Communication With Battery Energy Control Module "B"

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

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U0112 — Lost Communication With Battery Energy Control Module “B”