U012D: Lost Communication With Generator A Control Module

What it means

Lost Communication With Generator A Control Module: the control module has detected this fault condition.

At a glance

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

How it works

Generator A Control Module manages or reports operation of generator A and shares data with other vehicle controllers over the communication network. This code sets when a controller does not receive the expected messages from that specific module, commonly because its power, ground, network wiring, or gateway message path is interrupted.

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

• 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. Record freeze-frame data and scan all modules for related communication or charging-system faults; note whether Generator A Control Module alone is unavailable.
2. Check battery and charging-system condition, then inspect the module’s power and ground fuses and connections against the wiring diagram.
3. Inspect the Generator A Control Module connector and accessible CAN wiring for corrosion, loose terminals, moisture, or physical damage.
4. Use a scan tool to check whether the module responds and whether the gateway can see and route its messages.
5. If the module has correct power and ground, test the CAN circuit and termination according to the manufacturer’s procedure and specification.

Common fixes

• Correct a weak battery or charging-system issue that is disrupting module voltage.
• Repair a blown fuse, poor ground, or interrupted power feed to Generator A Control Module.
• Clean or repair a loose, corroded, or damaged module connector.
• Repair an open, short, or damaged CAN wire in the module’s network path.
• Address a verified gateway routing fault or replace the module only after its supply and network have passed checks.

Can I keep driving?

If charging warnings, reduced electrical power, or drivability changes occur, avoid unnecessary trips and stop safely if the vehicle becomes difficult to control or systems begin shutting down. A communication fault can hide generator-related information from other controllers, so have the cause checked promptly.