Body control module (BCM) codes

How its codes differ

• U0140 is stored by another module that stopped hearing from the body control module. Like other lost-communication codes, it is more often network wiring, a connector, power or ground than a failed module.
• Because the body module has many fuses and grounds, a supply problem can knock it off the network while the module itself is fine. Check battery voltage and the module's fuses before blaming it.
• Odd electrical behaviour (lights, horn or hazards working on their own) together with U0140 makes the module itself more likely; a single intermittent fault may instead be the battery, alternator, a fuse or a relay.

Codes

• U0140

  Lost communication with the body control module

  Severity: Inspect soon

Signs it's failing

• U0140 stored in other modules
• Locks, windows, lights or wipers not working, or working on their own
• Several warning lights at once
• A battery that runs flat when the module keeps loads switched on
• Starting trouble on vehicles where the module is part of the anti-theft system

How to test it

1. Read codes in all modules with a scan tool and note which module stored U0140. Fix any power, battery or network codes first. (Low risk)

2. Have the battery and charging system tested, and with the ignition off look over the body module fuses for a blown one. (Low risk)

3. Network wiring tests, programming and replacing the body control module are jobs for a shop. (Best left to a shop)

   Warning: A replacement body module has to be programmed to the vehicle and the key or immobilizer relearned, or the engine may not start; some vehicles also need a tire pressure sensor relearn.

After the repair

• After a module replacement, confirm the shop finished the programming, the key or immobilizer learn and any tire pressure sensor learn.
• Check that locks, windows, lights and wipers all work, and clear history codes in every module.