U0296: Lost Communication With AC/DC Converter Control Module A

What it means

The vehicle bus reports loss of communication with AC/DC converter (on-board charger) module A. Charging from AC sources cannot be controlled and the high-voltage battery does not refill via this path.

At a glance

• Usually lights the warning light of the system that lost communication
• The engine or gearbox may go into limp mode

How it works

AC/DC converter control module A manages an onboard conversion function involved in charging the high-voltage battery from an AC source. This code sets when expected network messages from module A stop arriving, so AC charging may be unavailable or interrupted.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules for freeze-frame and charging-system codes, and confirm whether module A alone is offline or other charging controllers also report communication loss.
2. Check the vehicle's charge status and whether the fault occurs with AC charging; note any charging interruption or warning without repeatedly reconnecting if the system reports a fault.
3. Inspect the accessible low-voltage connector and harness for module A for looseness, water, corrosion or damage; do not open high-voltage charging components.
4. Check the module's specified low-voltage power and ground, then test its network wiring for opens, shorts or poor connections using manufacturer procedures.
5. If supplies and network wiring are correct, follow manufacturer diagnostics to assess module A and its gateway; high-voltage work should be left to qualified personnel.

Common fixes

• Repair a loose, corroded or damaged low-voltage connector at converter control module A.
• Repair an open or short in the network wiring to module A.
• Restore module A's specified power or ground by repairing the confirmed feed, fuse or ground fault.
• Correct a verified gateway routing problem that prevents communication with module A.
• Replace module A only after its low-voltage supply and network path test correctly.

Can I keep driving?

The vehicle may still run on its remaining charge, but AC charging may not replenish the battery, so plan only a trip within the available range. Stop somewhere safe if charge becomes low; do not rely on this AC charging path until it is working.