U0296

Code

Generic U — Network/User

Lost Communication With AC/DC Converter Control Module A

Brand: Generic

Type: U — Network/User

Views: UK: 30 EN: 32 RU: 29

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty or powered-off AC/DC converter control module
Blown fuse or open relay supplying the module
Open or shorted wiring, damaged connectors, or corrosion at the module harness
CAN bus wiring fault or missing termination
Network interference or short to battery/ground
Faulty gateway or another module acting as bus bridge

Symptoms

Malfunction Indicator Lamp (MIL) or warning messages related to charging/conversion
On-board charger, DC/DC converter or accessory power unavailable or disabled
Charging faults or reduced charging rate (EV/HEV)
Other modules reporting related communication DTCs
Possible limp-home mode or restricted functionality

What to check

Read all network DTCs and note occurrence/ freeze data from vehicle scan tool
Check for additional related communication codes in other modules
Verify presence of module power and ground (check fuses, relays, harness) with key ON
Visually inspect AC/DC converter harness and connector for damage, corrosion, or water intrusion
Measure CAN bus voltages at the module connector (CAN_H and CAN_L) and at gateway/ECU connector
Measure bus termination resistance (~60 ohms across CAN_H and CAN_L with power off)

Signal parameters

CAN bus recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (common-mode) when idle
CAN bus dominant voltages: CAN_H ≈ 3.5 V and CAN_L ≈ 1.5 V during transmissions
Differential voltage between CAN_H and CAN_L ≈ 2.0 V when dominant
Termination resistance ≈ 60 Ω between CAN_H and CAN_L (two 120 Ω in parallel)
Module supply voltage: ignition-switched 12 V (or vehicle-specific supply) present with key ON
Expected periodic heartbeat/message transmission from converter control (absent when fault present)

Diagnostic algorithm

Connect a diagnostic scan tool and retrieve all stored/active DTCs and freeze frame data. Note any additional communication or power-related codes.
Verify vehicle-specific safety procedures for high-voltage systems before working on AC/DC components. Isolate high-voltage if required.
Perform a visual inspection of the AC/DC converter module, connector, and harness for damage, corrosion, or contamination. Repair or replace damaged wiring/connector as needed.
With ignition ON, confirm module supply and ground at the module connector. Check related fuses and relays; replace any blown fuses and test relays.
Using a multimeter/oscilloscope, measure CAN_H and CAN_L voltages at the module connector and at a known-good node. Compare to expected signal parameters.
With vehicle power OFF, measure termination resistance across CAN_H and CAN_L. Replace missing/failed termination if not ≈60 Ω.
If bus wiring and power are good but communication is absent, try waking the module with the scan tool or power-cycle the vehicle control modules. Re-scan for codes.
Swap with a known-good module only if donor is identical and vehicle-specific procedures permit. Use caution with high-voltage systems.
If wiring, power/ground, and network integrity are confirmed and module still does not communicate, consult manufacturer technical service information for module reprogramming or replacement.
After repairs, clear codes and road/test to confirm issue is resolved and ensure no intermittent communication faults reappear.

Likely causes

Loose, corroded, or disconnected module connector
Module not receiving ignition-switched 12V (or supplied voltage) due to fuse/relay fault
CAN bus wiring open/short or missing/failed termination resistor
Module internal failure

Fault status

⚠️ Status

Lost communication with AC/DC converter control module A — the control network is not receiving expected messages from the converter control module; check module power, grounds, connectors and CAN bus.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours