U0078Control Module Communication Bus F Off
- Generic OBD-II code · Network
- How the car detects it
- At GM the bus behind U0078 is often the single-wire low-speed GMLAN that ties body modules together. Equinox and Terrain models from 2010 to 2015 set it with lost-communication codes for body module, cluster and liftgate when water corrodes connector X901 above the liftgate glass. On the 2013-16 Acadia the low-speed wire to the remote door lock receiver got pinched between the rear HVAC duct and the roof, giving intermittent no-crank, a dead radio and erratic gauges. A poor body control module ground at G218 on the 2015 Escalade produced U0078 together with U0073. Because these modules handle comfort and access, owners mostly notice dark interior lights, a dead liftgate or blank displays. GM's published OBD tables do not list U0078, so no MIL type is documented.
- What you may notice
- Interior lamps or liftgate inoperative
- Radio, climate panel or cluster go blank
- Intermittent no-crank
- Likely causes
- LikelyWater intrusion and corrosion in a body harness connector
- PossibleLow-speed bus wire pinched behind trim or headliner
- PossiblePoor ground of the body control module
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.