U025B: Lost Communication With Special Purpose Vehicle Control Module C

What it means

A control module has stopped receiving expected messages from special purpose vehicle control module C. The code identifies the communication loss; upfitted functions controlled by that module may be affected.

How it works

Special purpose vehicle control module C handles its designated upfitted functions and sends status messages over the vehicle network. This code sets when a monitoring module does not receive the expected messages from module C.

Common causes

Most likely first.

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

Symptoms

• Functions controlled by the special purpose module may be unavailable
• A communication fault may be stored

How to diagnose it

1. Save freeze-frame data and scan other modules for network codes to see whether communication loss is confined to module C.
2. Check which upfitted functions are unavailable and confirm their link to special purpose vehicle control module C for this vehicle.
3. Inspect module C's connectors and bus wiring for loose or corroded terminals, chafing, damaged insulation, or an open or short.
4. Check module C's power and ground circuits against the manufacturer's procedure, since loss of either can take the module offline.
5. If power and ground are correct, test the network wiring at module C for opens or shorts following the manufacturer's procedure.

Common fixes

• Reconnect and secure a loose connector at special purpose vehicle control module C.
• Repair damaged bus wiring or corroded connector terminals serving module C.
• Restore the module's power or ground connection if faulty.
• Replace module C if its power, ground, and network circuits check out but it still does not communicate.

Can I keep driving?

The code may affect only equipment added for a special vehicle use, but the consequences depend on what module C controls. Do not use affected equipment, and avoid driving if it is needed for safe operation.