OBD-II code U0104 indicates that the powertrain control module (PCM) has lost communication with the cruise control module over the vehicle's Controller Area Network (CAN) bus. This typically means the cruise control system will be disabled until the issue is resolved.
The cruise control module itself may have an internal failure, preventing it from communicating on the CAN bus. This is a common cause, especially in older or high-mileage vehicles.
Damaged, corroded, or loose wiring or connectors between the cruise control module and the CAN bus can disrupt communication. Check for chafing, moisture intrusion, or poor connections.
An open or short circuit in the CAN high or CAN low wires can prevent communication between modules. This may affect other modules if the issue is widespread.
A blown fuse or failed relay supplying power to the cruise control module can cause a loss of communication. Check the fuse box and relay for the cruise control system.
Low voltage or voltage spikes from a weak battery or faulty alternator can disrupt CAN bus communication. Ensure the battery and charging system are functioning properly.
While uncommon, a failure in the PCM's CAN transceiver or internal circuitry could cause a loss of communication. This should only be considered after all other causes are ruled out.
Yes, the vehicle is typically drivable with U0104, as the code only affects the cruise control system. However, address the issue promptly to restore cruise control functionality and prevent potential CAN bus issues from affecting other systems.
No, the PCM is rarely the cause of U0104. This code is almost always triggered by a failure in the cruise control module, its wiring, or power supply. Replacing the PCM should only be considered after all other potential causes have been thoroughly checked.
Intermittent operation suggests a loose connection, damaged wiring, or a failing cruise control module. Inspect the wiring and connectors for signs of wear or corrosion, and test the module's power and ground supplies.
Resetting the battery may temporarily clear the code, but it will likely return if the underlying issue (e.g., faulty module, wiring problem) is not addressed. Focus on diagnosing and repairing the root cause.