U3026Control Module A Disable Circuit Low
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- U3026 is logged when the disable line to module A sits below its valid voltage range, typically because it is shorted to ground. What that means depends on the polarity the maker chose. In the Siemens control unit of patent US7596436B2 the enable signal is high for run and low for shutdown, and a monitoring circuit cuts the output stages by pulling the shutdown paths to vehicle ground. With such active-low logic a short to ground looks exactly like a permanent shutdown command, so module A stays off and the driver loses that function, although nothing else is wrong. Where low is the run state, the danger is the opposite, since the shutdown can no longer be signalled. No manufacturer documents U3026 publicly. Look for a chafed wire touching the body between the two modules.
- What you may notice
- Module A stays switched off, function unavailable
- Warning message for the affected system
- Likely causes
- LikelyDisable wire chafed through and touching body ground
- PossibleMoisture in a connector creating a leak path to ground
- RareSupervising module holding the line low permanently
- Repair
- Hard · Usually a job for a workshop.Typical cost: €50 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.