I'm sorry to hear that you're having trouble with your truck, Nhanlam. The SPN 000639 code indicates there is an issue with the J1939 network, which is the communication system used by various components in the truck.
To fix this issue, you can try the following steps:
1. Check the connectors and wirings: A loose or damaged connector or wiring can cause the J1939 network to fail. Inspect the connectors and wiring to make sure they are clean and tight.
2. Check the network module: The network module controls the communication of the J1939 network. Sometimes the module may fail, and if it does, then the network may not work. Check the module to see if it is working correctly.
3. Bring it to a professional: If you’re unsure or don’t know how to identify and diagnose the problem, it may be best to bring your truck to a professional mechanic who can help you to resolve the issue.
In terms of preventing similar issues in the future, regular maintenance and inspections can go a long way in keeping your truck running smoothly. Make sure to keep up with your truck's regular maintenance schedule, like changing the filters, oil, and coolant. Additionally, keep an eye out for any unusual sounds, vibrations, or smells, and address them promptly to avoid any potential problems down the road.