Power Take Off Mode

A Power Take-Off (PTO) unit refers to an engine driven output provision for the purposes of powering auxiliary equipment (e.g., a dump-truck bed, aerial bucket, or tow-truck winch). The OBD-II regulations have historically accommodated PTO by requiring the software to set all I/M readiness bits to "not complete" when PTO was engaged and reset them to their previous state when PTO was disengaged.

The 2015 MY OBD-II regulations have changed the requirement for PTO mode. This is in reaction industry request to accommodate PTO while the vehicle is stationary (stationary PTO) or while the vehicle is moving (mobile PTO). In mobile PTO, some OBD monitors may not run or may run at reduced frequency. The changes to the OBD-II regulations accommodate vehicles being I/M tested while PTO is engaged.

For the 2015 MY, the OBD II system is required to track the cumulative engine runtime with PTO active and set all the OBD II I/M readiness bits to "not complete" if 750 minutes of cumulative engine runtime with PTO active has occurred and all OBD monitors have not yet completed. The PTO timer pauses whenever PTO changes from active to not active and resumes counting when PTO is re-activated. The PTO timer is reset to zero after all the affected monitors have completed. If an OBD monitor is completely disabled by PTO mode, the affected IUMPR numerator and denominator must also be disabled.

This new requirement provides a 750 minute allowance to run all OBD monitors before all the I/M readiness bits are set to "not complete" in order to better accommodate vehicles that have monitors that run with reduced frequency in PTO mode or have monitors that don't run at all.