P2610

P2610 means the PCM detected an internal fault with its engine-off timer — the counter that tracks how long the engine has been off between key cycles, used by evaporative-emissions monitors, cold-start logic, and ambient-temperature rationality checks. The timer should count smoothly from 0 to 86,400 seconds (24 hours) during a soak, then reset; an internal fault means the counter is stuck, jumping, or losing time across power-down cycles. Shop-floor ladder, cheapest first: (1) Scan-tool read the freeze-frame and confirm the code set during a key-off-to-key-on transition (typical) vs during run (rare and points to PCM corruption). (2) Check PCM battery-feed circuit: a weak hold-power feed (typical fuse-fed, 12V always-hot) can cause the timer to reset randomly; backprobe the keep-alive memory (KAM) feed at the PCM connector and confirm 12V with the key off; voltage drop more than 0.5V from battery means corrosion or a failing fuse panel. (3) Battery condition: a marginal battery that drops below ~9V during cold cranking can corrupt KAM and trigger P2610; load-test the battery and replace if it fails. (4) Aftermarket parasitic-draw devices (dashcams, hardwired radar detectors, aftermarket alarms) on the keep-alive feed are a known cause — disconnect them and clear the code. (5) If hardware checks pass, PCM reflash to the latest calibration often clears the fault; if reflash doesn't take, the PCM is the part. DO NOT probe HV orange-wire circuits with a standard multimeter. Always service HV with Class 0 1000V gloves, isolation tester (Megger), and DC-rated lugged probes. Pack contactor stuck-closed (P0AF1/P0AF2) is the only condition where the orange-wire bus may be live AFTER the service plug is removed. NEVER assume zero potential — always measure with an HV-rated meter.

Vehicle-specific patterns: 2003-2014 GM full-size trucks/SUVs (Silverado, Sierra, Tahoe, Suburban, Yukon) are the most common P2610 ticket — the Saginaw-built PCMs of this generation have a known KAM-corruption failure mode, often triggered by a marginal battery or a low-voltage event during winter starts, and GM issued multiple TSBs for PCM reflash; if reflash doesn't hold, the PCM gets replaced. 2011-2016 Ford F-150 EcoBoost and 2011-2014 Mustang see P2610 from a similar PCM internal-watchdog fault, sometimes paired with intermittent stalling. 2005-2010 Chrysler 300 / Charger / Magnum 5.7L Hemi sees it from a failing instrument-cluster gateway that corrupts the PCM keep-alive bus. 2007-2012 Nissan Altima / Maxima sees it from a known ECM ground-strap corrosion issue at the chassis tie-point. Estimated repair: $0 (clear code after battery replacement) to $1,200 (PCM replacement + programming).