I have Odyssey 2006 - EXL

DTC P0685: PCM Power Control Circuit/Internal Circuit Malfunction

NOTE: If the problem does not return after you clear the DTC, or if this DTC is stored intermittently, check for loose terminals at the IGP line connectors before replacing the PCM.

Turn the ignition switch ON (II).
Clear the DTC with the HDS.
Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.

NO - Intermittent failure, system is OK at this time.