How-To: Power Off/On Resets for PCM, GEM System Re-Boot
 

You often hear to disconnect your battery for a long period of time (30 minute, 1 hour, etc.) to reset PCM, GEM, and other control modules. The reason for this long time is to discharge the large internal decoupling capacitors that are continuously powered. The current that these circuits pull is very low, so the discharge time is very long.

To eliminate this long discharge time, remove the negative battery cable from the battery, and touch the positive battery terminal with it for only a second or two. This provides a current path to discharge the decoupling capacitors.