Since you replaced the transmission and fuel lines, it’s possible something indirectly related to the braking systems was disconnected or disturbed. Here are a few things you can check:
1. Battery or Power Supply: Ensure the battery is fully charged and all grounds are secure. Low voltage or weak connections can cause issues with the ABS, electronic braking, and trailer braking systems, as they are sensitive to voltage fluctuations. Disconnecting the battery during repairs could reset some modules or cause them to throw errors temporarily.
2. Grounding Wires: During the transmission replacement, any ground wires that may have been disconnected or loosened should be checked. Many electronic systems, including ABS and braking modules, share grounding points. A loose or missing ground can lead to multiple system errors.
3. Transmission Control Module (TCM): Since you replaced the transmission, the TCM may need to be reinitialized or relearned. Some of the braking systems can communicate with the TCM, and if the module isn't properly calibrated or linked after replacement, it could cause system warnings without generating specific codes.
4. Wheel Speed Sensor Wiring: Although you mentioned the wheel sensors and wiring are in place, double-check the connections. When the transmission was removed, it's possible that a wire or connector related to the ABS system was disturbed, leading to the error messages.
5. CAN Bus Communication: The ABS, braking systems, and trailer braking system communicate over the truck’s CAN bus network. If any wiring or modules related to the CAN bus were disconnected or damaged during your repairs, it could cause these warnings. Make sure all connectors, particularly those around the transmission and engine bay, are fully seated.
6. Scan Tool Compatibility: Since your scanner isn't showing any codes, you might need a more advanced scan tool that can read manufacturer-specific modules, especially for ABS, braking systems, and other electronic control units (ECUs). A dealership or professional scan tool could provide deeper insight into what’s triggering those warnings. If you need a scan tool recommendation, my shop uses these laptops and they work great.
https://dieselscanners.com/products/diesel-diagnostic-laptop-scanner-tuner-truck-repair
Check over these connections, especially ground points and wiring harnesses, and you may find something was left disconnected or disturbed during the repair. If the problem persists, you might need to have the truck scanned with a tool that can read the ABS and brake control modules.