by Trail X » Thu Jan 22, 2015 2:29 pm
Larger tires shouldn't affect the EBTCM (ABS module). I believe the EBTCM is simply the valve block that controls the ABS response. I believe that the ABS brains are in the PCM. My truck isn't CAN though, so my FSM doesn't cover the communications bus on the 2006+ trucks.
If you're losing a can bus intermittently, I'd really suspect a bad connection. If its constant, then its likely a bad module.
See if your ABS works first by testing it on a gravel lot or wet pavement. That should tell us if the module has any communication over the bus. If its not working all the time, then you have a bad connection or a bad module that's talking too much and taking down the bus. If the ABS works, but you still get intermittent CELs for a dropping bus, then it may be a bad connection and you'll need to try to identify where the spotty connection is occuring. Could be a lose plug or pin, or a wire that has been compromised. If you get into trying to troubleshoot a bad connection, you'll need schematics and a lot of knowledge of a multimeter.
If a module is taking the bus down, finding said module will probably require a CAN sniffer of some sort - I hate to say it, but it might be a dealer only repair.