C0265

C0265 is the EBCM relay circuit code, indicating the main relay that powers the ABS solenoids and pump-motor control logic is not behaving as expected — either the EBCM cannot energize the relay, the relay coil is open, or the contacts are stuck/welded. Cheapest first: clear it, see if it returns immediately at key-on (hard fault) or only after a few drive cycles (intermittent contact wear). Pull the ABS relay from the underhood fuse box and bench-test it with a 12V battery and a test light — coil should click crisply and contacts should pass continuity only when energized; swap it with an identical-pinout relay from the horn or fuel-pump circuit for a $0 confirmation. Check the relay socket terminals for spread/burnt pins and the EBCM control wire (usually a low-side driver from the module) for the expected pull-to-ground when commanded. Live-data check: most scan tools can command the ABS relay on/off — you should hear an audible click and see the ABS solenoid feed circuit voltage rise from 0V to battery voltage. The expensive misdiagnosis pattern is the C0110/C0265 paired code on GM Kelsey-Hayes 325 systems, where techs replace the relay (correct) but never address the cold-solder joint inside the EBCM that re-sets the code in 200 miles, then condemn the whole module unnecessarily.

Vehicle-specific patterns: 1999-2007 GM Silverado/Sierra/Tahoe/Suburban — internal EBCM solder joints crack from underhood heat cycling, the rebuilders specifically target this. 2003-2008 Chevy TrailBlazer/GMC Envoy — relay socket terminals spread and lose contact pressure. 2005-2009 Pontiac Grand Prix — ABS relay coil opens, $12 part. 2001-2006 Chevy Silverado HD 2500/3500 — combined C0265+C0110+C0161 pattern is the Kelsey-Hayes failure signature; rebuild service is the cost-effective fix. Estimated repair: $12 to $1,400.