U019B: Lost Communication With Battery Charger Control Module A

What it means

ECU lost communication with battery charger control module A (on-board charger for HV battery on plug-in hybrids/EVs).

At a glance

• Usually lights the warning light of the system that lost communication

How it works

Battery Charger Control Module A manages the vehicle's on-board charger, which converts external charging power for the high-voltage battery. U019B sets when the control module stops receiving expected network messages from charger module A, so the vehicle may be unable to coordinate charging.

Common causes

Most likely first.

1. Module unpowered
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Battery charging functions may be unavailable
• Other communication codes

How to diagnose it

1. Save freeze-frame data and scan all modules for current codes, noting whether the charging system or gateway has additional communication faults.
2. Check the charging display and charge status to confirm whether the vehicle recognizes the on-board charger and whether the fault occurs during plug-in charging.
3. With the vehicle safely powered down as specified by the manufacturer, inspect the charger's low-voltage supply, grounds, connectors, and accessible wiring for damage or corrosion.
4. Check for gateway faults that could prevent messages from charger module A reaching other modules.
5. Have the charger communication network and terminating resistance tested against the manufacturer's specification; do not probe high-voltage connections.

Common fixes

• Repair damaged or corroded low-voltage wiring or connector terminals at charger module A.
• Restore the module's low-voltage power or ground supply and address the cause of any blown fuse.
• Correct a gateway routing or configuration issue.
• Repair the network wiring or replace a terminating resistor that fails the manufacturer's specification.

Can I keep driving?

The vehicle may not charge its high-voltage battery normally, so avoid a trip that depends on charging or electric range until charging operation is confirmed. Do not handle high-voltage components; stop using the vehicle if it displays a high-voltage system warning.